I've Been Killing Slimes for 300 Years and Maxed Out My Level

I've Been Killing Slimes for 300 Years and Maxed Out My Level (Japanese: スライム倒して300年、知らないうちにレベルMAXになってました, Hepburn: Suraimu Taoshite Sanbyaku-nen, Shiranai Uchi ni Reberu Makkusu ni Nattemashita) is a Japanese isekai light novel series written by Kisetsu Morita and illustrated by Benio. It was serialized online since 2016 on the user-generated novel publishing website Shōsetsuka ni Narō and, in the following year, it was acquired by SB Creative, who published the first light novel volume in 2017. The light novel has been licensed in North America by Yen Press, who published the first volume in April 2018. It has received a manga adaptation by Yūsuke Shiba in the same year as its debut of the light novel in Square Enix's Gangan Online website, also licensed by Yen Press. An anime television series adaptation by Revoroot aired from April to June 2021. A second season by Teddy is set to premiere in April 2025. The series has also spawned various spin-off novels.

I've Been Killing Slimes for 300 Years and Maxed Out My Level
Cover of the first volume of the light novel, featuring Azusa Aizawa
スライム倒して300年、知らないうちにレベルMAXになってました (Suraimu Taoshite Sanbyaku-nen, Shiranai Uchi ni Reberu Makkusu ni Nattemashita)
Genre	Isekai
Novel series
Written by	Kisetsu Morita
Published by	Shōsetsuka ni Narō
Original run	June 23, 2016 – November 18, 2021
Light novel
Written by	Kisetsu Morita
Illustrated by	Benio
Published by	SB Creative
English publisher	NA: Yen Press
Imprint	GA Novel
Demographic	Male
Original run	January 14, 2017 – present
Volumes	25
Further information Manga Illustrated by Yūsuke Shiba Published by Square Enix English publisher NA: Yen Press Magazine Gangan Online Manga Up! Demographic Shōnen Original run June 29, 2017 – present Volumes 15 Light novel I Was a Bottom-Tier Bureaucrat for 1,500 Years, and the Demon King Made Me a Minister Written by Kisetsu Morita Illustrated by Benio Published by Square Enix (ep. 1–2, 4, 6, 8, 12) SB Creative (ep. 3, 5, 7, 9–11,13–) English publisher NA: Yen Press Imprint GA Novel Magazine Gangan Online (ep. 1–2, 4, 6, 8, 12) Demographic Male Original run July 13, 2017 – August 11, 2022 Volumes 1 Light novel Food for an Elf Written by Kisetsu Morita Illustrated by Benio Published by Square Enix English publisher NA: Yen Press Imprint GA Novel Magazine Gangan Online Manga Up! Demographic Male Original run April 12, 2018 – June 28, 2018 Manga I Was a Bottom-Tier Bureaucrat for 1,500 Years, and the Demon King Made Me a Minister Illustrated by Meishi Murakami Published by Square Enix English publisher NA: Yen Press Magazine Gangan Online Manga Up! Demographic Shōnen Original run January 31, 2019 – August 20, 2020 Volumes 3 Light novel Red Dragon Women Academy Written by Kisetsu Morita Illustrated by Benio Published by Square Enix (ep. 1–6) Shōsetsuka ni Narō (ep. 7) SB Creative (ep. 8–) Imprint GA Novel Magazine Manga Up! (ep. 1–6) Gangan Online (ep. 1–6) Shōsetsuka ni Narō (ep. 7) Demographic Male Original run July 15, 2019 – December 14, 2021 Novel series The White Journey of Margrave Written by Kisetsu Morita Published by Shōsetsuka ni Narō Imprint GA Novel Demographic Male Original run March 25, 2021 – March 29, 2021 Manga Red Dragon Women Academy Illustrated by Hitsujibako Published by Square Enix English publisher NA: Yen Press Magazine Manga Up! Gangan Online Demographic Shōnen Original run March 29, 2021 – present Volumes 2 Anime television series Directed by Nobukage Kimura (S1) Kunihisa Sugishima (S2) Produced by Yutaka Kashiwagi Takumi Itou Daichi Amano Shouta Komatsu Yoshinori Hasegawa Jun Morita Souji Miyagi Yuuichi Izumi Tadayuki Akita Tomoyuki Oowada Mitsuhiro Nanbara Written by Tatsuya Takahashi (S1) Naohiro Fukushima (S2) Music by Keiji Inai Studio Revoroot (S1) Teddy (S2) Licensed by Crunchyroll SA/SEA: Muse Communication Original network AT-X, Tokyo MX, BS11 English network SEA: Animax US: Crunchyroll Channel Original run April 10, 2021 – present Episodes 12

Plot

After living a painful life as an office worker on Earth, Azusa ends up dying from overworking. She finds herself reincarnated as an undying, unaging witch in a new world, and now she vows to spend her days as pleasantly and stress-free as possible. She makes a living by hunting slimes, the easiest targets. But after centuries of doing this simple job, she has become extremely powerful and finds that she can no longer maintain her low-key lifestyle.

Characters

Azusa Aizawa (アズサ・アイザワ / 相沢梓, Azusa Aizawa / Aizawa Azusa)

Voiced by: Aoi Yūki (drama CD, anime) (Japanese); Skyler Davenport (English)

A former Japanese office worker reincarnated as an immortal witch, called "the Witch of the Highlands" (高原の魔女, Kōgen no Majo). Weary of any overwork and excitement following her untimely death in her old life, she strives for an easy tune of existence, but once word gets out of her unprecedented prowess, she finds herself beleaguered by challengers trying to prove themselves on her, or all sorts of people willing to join her. However, she is compassionate and in time becomes very protective of her adopted family, much to the chagrin of anyone who deliberately endangers them.

Laika (ライカ, Raika)

Voiced by: Kaede Hondo (drama CD, anime) (Japanese); Rachelle Heger (English)

A roughly 300-year-old shape-shifting red dragon girl. Originally arrogant, she came to Azusa to fight her and prove herself to be stronger than her. After getting soundly beaten by Azusa, she joins her as her first apprentice and housekeeper, eventually becoming her adoptive younger sister. She has a rivalry with Flatorte.

Falfa (ファルファ, Farufa)

Voiced by: Sayaka Senbongi (drama CD, anime) (Japanese); Lizzie Freeman (English)

An about 50-year-old slime spirit girl, and the elder of twin sisters. She is one of Azusa's adoptive daughters. Both she and her sister Shalsha are reincarnations of the slime creatures that Azusa killed for a living; but while Shalsha is initially deeply resentful towards Azusa at first, Falfa adores her and considers her their "mother".

Shalsha (シャルシャ, Sharusha)

Voiced by: Minami Tanaka (drama CD, anime) (Japanese); Suzie Yeung (English)

Falfa's younger slime spirit twin sister. She is one of Azusa's adoptive daughters. Driven by feelings of revenge against Azusa for killing all the slimes, she learned a type of magic which is effective against one specific race only, but in turn is potent enough to counter even Azusa's magic; she is also very learned in magic lore. After being very easily beaten by Laika, Shalsha and Falfa join Azusa's household upon her invitation. In turn, she abandoned her desire for revenge upon learning that she is not the only one targeting slimes. She is very inquisitive, and habitually takes notes of anything new she comes across.

Halkara (ハルカラ, Harukara)

Voiced by: Sayaka Harada (drama CD, anime) (Japanese); Xanthe Huynh (English)

A young (about 225-year-old) female elf apothecary woman from Frant Province with very abrupt mood swings and a voluptuous build. She invented an extremely popular, alcohol-based energy drink; but when the demon lord Beelzebub drank from it, she became sick (from overworking after getting addicted to it) and then went after Halkara, whereupon the elf, believing that Beelzebub wanted in fact revenge, fled to Azusa for protection. After being given shelter, and after the misunderstanding with Beelzebub is cleared, Halkara decides to stay with Azusa and restart the production of her energy drink. She is very knowledgable about mushrooms, but scatterbrained and accident-prone.

Beelzebub (ベルゼブブ, Beruzebubu)

Voiced by: Manami Numakura (drama CD, anime) (Japanese); Erica Mendez (English)

An about 3,000-year-old high-ranking female demon, the Agriculture Minister of the Demon Realm, and Lord of the Flies. Chasing after Halkara after getting addicted to her energy drink (so that its production could be re-started) she challenges Azusa to a fight, but collapses from exhaustion and is nursed back to health by her and Halkara. After the misunderstanding was cleared, she leaves peacefully, but vows to come back to settle her score with Azusa (which she ultimately loses) and get more of Halkara's drink, although she begins to settle in as one of Azusa's "family", eventually becoming Azusa's adoptive older sister.

Flatorte (フラットルテ, Furattorute)

Voiced by: Azumi Waki (drama CD, anime) (Japanese); Amber Lee Connors (English)

An over 400-year-old blue dragon girl who first meets Azusa and her extended family while she and her flock attempt to disrupt the wedding of Laika's older sister, out of simple jealousy that her blunt demeanor drove away her own fiance. After Azusa single-handedly thrashes the aggressors, and a final act of aggression is stalled by Beelzebub, she is forced to sign a peace treaty between the red and blue dragons. Afterwards, as part of her peace obligations, she also (much to Laika's disgust, which results in them becoming rivals) joins Azusa's troupe—the only alternative being to commit suicide due to her culture.

Rosalie (ロザリー, Rozarī)

Voiced by: Riho Sugiyama (drama CD, anime) (Japanese); Anne Yatco (English)

A ghost girl who died about 200 years previously at the age of 15. The daughter of a merchant who had fallen on hard times, she committed suicide after learning that her father wanted to sell her off as a prostitute. Her restless ghost began haunting the merchant's estate, which later became the site for Halkara's new energy drink factory. After being caught by Azusa, Halkara and Beelzebub, she is, with some effort, relocated to Azusa's house and joins her adopted family.

Fatla (ファートラ, Fātora)

Voiced by: Miku Itō (anime) (Japanese); Veronica Taylor (English)

A leviathan woman, Beelzebub's secretary, and Vania's older sister. She and Vania are both shapeshifters, able to assume the form of a gigantic, flying whale. Despite the myth that leviathans are water creatures, they are actually air dwellers, and are usually employed as living transportation (complete with a resort hotel on their backs) by demons, devils and their privileged guests. To fulfill this obligation, both sisters work in tandem: While one does the transport, the other uses the hotel facilities (especially the bath) to relax.

Vania (ヴァーニア, Vānia)

Voiced by: Ari Ozawa (anime) (Japanese); Allegra Clark (English)

A leviathan woman, Beelzebub's assistant secretary, and Fatla's younger sister.

Pecora / Provat Pecora Allières (ペコラ / プロヴァト・ペコラ・アリエース, Pekora / Purovato Pekora Ariēsu)

Voiced by: Yukari Tamura (drama CD, anime) (Japanese); Corina Boettger (English)

An over 1,000-year-old demon girl and the "King" of the Demon Realm from its capital city Vanzeld. Despite her awe-inspiring title, her natural form is a cute, petite girl with ram horns and three tails, and she is, most of the time, surprisingly cheerful and informal. She has also a submission complex; after being accidentally knocked out by Halkara, and with Azusa beating her in a duel over Halkara's life, she gladly submits to her "conqueror".

Smart Slime (賢いスライム, Kashikoi Suraimu, lit. 'Wise slime')

In manga: Smarsly / Smart Slime (賢スラ / 賢いスライム, Kensura / Kashikoi Suraimu)

In anime: Intellie / Intelligent Slime (賢スラ / 賢いスライム, Kensura / Kashikoi Suraimu)

A normal slime which is completely black.

Smarsly (in manga) / Intellie (in anime) is name given to it by Azusa. (Shortened name is used in light novel volume 12 and later.)

Wizly / Wizard Slime (マースラ / 魔法使いスライム, Māsura / Mahō Tsukai Suraimu, lit. 'Magic user slime')

In anime: Magie / Magician Slime (マースラ / 魔法使いスライム, Māsura / Mahō Tsukai Suraimu)

Voiced by: Miyuri Shimabukuro (anime)

A magician slime girl who looks like 15-year-old blond girl, but is 300-year-old woman.

Wizly (in light novel and manga) / Magie (in anime) is name given to her by Azusa.

Fighsly / Fighter Slime (ブッスラー / 武道家スライム, Bussurā / Budōka Suraimu, lit. 'Budō (Japanese martial arts) expert slime')

In anime: Fightie / Fighter Slime (ブッスラー / 武道家スライム, Bussurā / Budōka Suraimu)

Voiced by: Ayasa Itō (anime) (Japanese); Veronica Taylor (English)

An about 300-year-old fighter slime girl whom Azusa and the others seek out when Falfa is stuck in slime form after getting a crick in her neck. She is very materialistic and considers fighting a means to collect more and more prizes. After being easily beaten by Azusa, she considers joining her as a martial arts apprentice, but instead becomes Beelzebub's apprentice after learning about the slimes that Azusa killed.

Fighsly (in light novel and manga) / Fightie (in anime) is name which she herself decided to use, and was not given to her by Azusa.

Eno (エノ, Eno)

Voiced by: Hikaru Tono (anime) (Japanese); Anairis Quiñones (English)

An over 150-year-old immortal witch, called "the Witch of the Grotto" (洞窟の魔女, Dōkutsu no Majo). Naive and deadly shy, but yearning for recognition, she usurps the title of "Highland Witch" to capitalize on Azusa's reputation and make herself some new friends. When Azusa hears of the fake, she confronts Eno and afterwards helps her in selling her mandragora-based medicines, which prove extremely popular. Her title stems from the location of her workshop, which is situated inside a hard-to-reach underground location, thus contributing to her initial lack of renown.

Pondeli (ポンデリ, Ponderi)

An undead catgirl who died 40 years ago after she became so lazy from boredom that she forgot to even feed herself. After rising from death, she became a graveyard security guard, but felt lonely without anyone keeping her company. Azusa solves the problem by suggesting to Beelzebub that Pondeli is made a demon casino gambler, since the catgirl is wickedly good at playing cards.

Leila

Laika's older sister, who marries later in the story.

Natalie

The current owner of Flatta's guild.

Kuku (クク, Kuku)

Voiced by: Kotori Koiwai (anime)

An about 80-year-old almiraj minstrel girl. She also has an alternate persona called Schifanoia, which she later abandons.

Yufufu (ユフフ, Yufufu)

A droplet spirit woman.

Sandra (サンドラ, Sandora)

Voiced by: Yui Ogura (anime)

An over 300-year-old mandragora girl.

Misjantie (ミスジャンティー, Misujantī)

A pine spirit woman. The being who mediated marriages.

Curalina (キュアリーナ, Kyuarīna)

An about 60,000 to 70,000-year-old jellyfish spirit and wandering artist woman.

Goodly Godly Godness (メガーメガ神, Megāmega Shin)

Voiced by: Kikuko Inoue (anime, drama CD)

The goddess. The very being who reincarnated Azusa into this world.

Muu / Muum Muum (ムー / ムーム・ムーム, Mū / Mūmu Mūmu)

A ghost girl. Sovereign of the ghost's kingdom of the dead. She died at 15 years old, and about 5,000 years have passed since her death.

The Goddess Nintan (ニンタン神, Nintan Shin)

The goddess of time. A goddess long worshipped in this world.

Wynona (シローナ, Shirōna)

A slime spirit girl born after Falfa and Shalsha.

White Slimes

Not much is known about them other than the fact that they are evil.

Wyverns

They are used as a faster way to travel up the World Tree.

Red Dragons

Laika's kind, who can also take the form of humans.

Blue Dragons

Flatorte's kind, who are known enemies to the red dragons until a peace treaty was formed by Azusa. Like the red dragons, they can take human forms.

Locations

Flatta village

This is the story's main setting. Azusa lives close to this village.

Mount Rokko

This volcano is the homeland of the red dragons. This is where Laika came from.

Demon Realm

A city where demons reside. This place is controlled by Pecora.

World Tree

A giant tree that has been hollowed out and turned into a tourist attraction. It has 108 floors, each containing different challenges.

Media

Light novels

Originally, the series was published by Kisetsu Morita on the user-generated web novel site Shōsetsuka ni Narō in 2016. The publisher SB Creative acquired the series and then began publishing it on their GA Novel imprint as a light novel in January 2017. Twenty-five volumes have been released as of August 2024.

No.	Original release date	Original ISBN	English release date	English ISBN
01	January 14, 2017	978-4-7973-9044-5	April 24, 2018	978-0-3164-4828-4
02	April 15, 2017	978-4-7973-9176-3	August 21, 2018	978-0-3164-4830-7
03	July 15, 2017	978-4-7973-9295-1	December 11, 2018	978-1-9753-2937-2
04	October 13, 2017	978-4-7973-9296-8	April 23, 2019	978-1-9753-8264-3
05	January 15, 2018	978-4-7973-9297-5 978-4-7973-9298-2 (special edition)	September 3, 2019	978-1-9753-8266-7
06	April 13, 2018	978-4-7973-9617-1	December 24, 2019	978-1-9753-8268-1
07	July 14, 2018	978-4-7973-9619-5 978-4-7973-9618-8 (special edition)	June 23, 2020	978-1-9753-1292-3
08	November 15, 2018	978-4-7973-9913-4	October 27, 2020	978-1-9753-1482-8
09	March 15, 2019	978-4-8156-0096-9 978-4-8156-0097-6 (special edition)	January 19, 2021	978-1-9753-1834-5
10	August 09, 2019	978-4-8156-0274-1	August 24, 2021	978-1-9753-1835-2
11	December 12, 2019	978-4-8156-0275-8	January 18, 2022	978-1-9753-3979-1
12	April 14, 2020	978-4-8156-0559-9 978-4-8156-0276-5 (special edition)	May 24, 2022	978-1-9753-4053-7
13	July 14, 2020	978-4-8156-0705-0	November 8, 2022	978-1-9753-4055-1
14	October 14, 2020	978-4-8156-0651-0 978-4-8156-0650-3 (special edition)	January 30, 2024	978-1-9753-4058-2
15	January 14, 2021	978-4-8156-0706-7	November 19, 2024	978-1-9753-6193-8
16	April 13, 2021	978-4-8156-0708-1 978-4-8156-0707-4 (special edition)	March 18, 2025	978-1-9753-8873-7
17	June 12, 2021	978-4-8156-1090-6	—	—
18	September 14, 2021	978-4-8156-1091-3	—	—
19	December 14, 2021	978-4-8156-1347-1	—	—
20	April 14, 2022	978-4-8156-1393-8	—	—
21	August 11, 2022	978-4-8156-1640-3	—	—
22	January 16, 2023	978-4-8156-1873-5	—	—
23	July 14, 2023	978-4-8156-2034-9	—	—
24	November 14, 2023	978-4-8156-2035-6	—	—
25	August 9, 2024	978-4-8156-2707-2	—	—
26	December 15, 2024	978-4-8156-2708-9	—	—

In the volumes 5 to 7, 20, and 21 of the light novel, a special story about the character Beelzebub was published at the end of those volumes. In September 2019, those stories were compiled into its own volume and the spin-off, called I Was a Bottom-Tier Bureaucrat for 1,500 Years, and the Demon King Made Me a Minister (ヒラ役人やって1500年、魔王の力で大臣にされちゃいました, Hira Yakunin Yatte 1500-nen, Maō no Chikara de Daijin ni Sarechaimashita), published by SB Creative on the GA Novel imprint with Kisetsu Morita and Benio as the author and illustrator, respectively.

No.	Original release date	Original ISBN	English release date	English ISBN
—	September 13, 2019	978-4-8156-0116-4	March 30, 2021	978-1-9753-1829-1

In the volumes 8 to 10 of the light novel, another spin-off light novel called Food for an Elf' (Japanese: エルフのごはん, Hepburn: Erufu no Gohan), a special story about the character Halkara was published at the end of those volumes.

In the volumes 11 to 13, 16, and 18 to 19 of the light novel, another spin-off light novel called Red Dragon Women Academy (レッドドラゴン女学院, Reddo Doragon Jogakuin, lit. Red Dragon Girls' Secondary School) a special story about the character Laika was published at the end of those volumes.

In the volume 17 of the light novel, another spin-off light novel called The White Journey of Margrave (Japanese: 辺境伯の真っ白旅, Hepburn: Henkyōhaku no Masshiro Tabi), a special story about the character Wynona was published at the end of those volume.

Manga

In June 2017, Square Enix began publishing a manga adaptation of the series by Yūsuke Shiba in their online website and smartphone app Gangan Online, with fifteen tankōbon volumes released as of August 2024.

No.	Original release date	Original ISBN	English release date	English ISBN
1	January 12, 2018	978-4-7575-5582-2	January 28, 2020	978-1-9753-3302-7
2	June 22, 2018	978-4-7575-5751-2	May 26, 2020	978-1-9753-0917-6
3	November 13, 2018	978-4-7575-5912-7	October 10, 2020	978-1-9753-0920-6
4	April 12, 2019	978-4-7575-6085-7	February 9, 2021	978-1-9753-0923-7
5	September 12, 2019	978-4-7575-6286-8	March 9, 2021	978-1-9753-1752-2
6	February 12, 2020	978-4-7575-6502-9	June 22, 2021	978-1-9753-1793-5
7	September 12, 2020	978-4-7575-6749-8	December 14, 2021	978-1-9753-3577-9
8	March 12, 2021	978-4-7575-7122-8 978-4-7575-7123-5 (special edition)	April 26, 2022	978-1-9753-4068-1
9	June 11, 2021	978-4-7575-7321-5	August 2, 2022	978-1-9753-4735-2
10	December 10, 2021	978-4-7575-7630-8	March 21, 2023	978-1-9753-4990-5
11	June 10, 2022	978-4-7575-7965-1	September 19, 2023	978-1-9753-7167-8
12	December 12, 2022	978-4-7575-8307-8	January 30, 2024	978-1-9753-7542-3
13	July 12, 2023	978-4-7575-8663-5	July 23, 2024	978-1-9753-9284-0
14	February 9, 2024	978-4-7575-9050-2	February 18, 2025	979-8-8554-1011-2
15	August 9, 2024	978-4-7575-9353-4	—	—

A manga adaptation of the spin-off light novel I Was a Bottom-Tier Bureaucrat for 1,500 Years, and the Demon King Made Me a Minister was launched on Square Enix's Gangan Online website and smartphone app, with Meishi Murakami reprising his work.

No.	Original release date	Original ISBN	English release date	English ISBN
1	September 12, 2019	978-4-7575-6287-5	April 20, 2021	978-1-9753-2410-0
2	February 12, 2020	978-4-7575-6503-6	December 28, 2021	978-1-9753-2412-4
3	September 12, 2020	978-4-7575-6750-4	April 26, 2022	978-1-9753-3805-3

A manga adaptation of the spin-off light novel Red Dragon Women Academy was launched on Square Enix's Manga UP! smartphone app, with Hitsujibako reprising his work.

No.	Original release date	Original ISBN	English release date	English ISBN
1	December 10, 2021	978-4-7575-7631-5	August 22, 2023	978-1-9753-6650-6
2	August 9, 2024	978-4-7575-9354-1	—	—

Anime

An anime television series adaptation was announced during a livestream for the "GA Fes 2019" event on October 19, 2019. The series is animated by Revoroot and directed by Nobukage Kimura, with Tatsuya Takahashi handling series' composition, Keisuke Goto designing the characters, and Keiji Inai composing the series' music. The series aired from April 10 to June 26, 2021, on AT-X, Tokyo MX, and BS11. Aoi Yūki performed the opening theme song "Gudafuwa Everyday" (ぐだふわエブリデー, Gudafuwa Eburidē, lit. Gudaguda and fluffy everyday), while Azumi Waki performed the ending theme song "Viewtiful Days!". Crunchyroll streamed the series outside of Asia. In Southeast Asia and South Asia, Muse Communication licensed the series. The company also has licensed the anime to Animax Asia for TV broadcasts. The company also has licensed the anime to Animax Asia for TV broadcasts.

In January 2022, it was announced that a second season was green-lit. The season will be animated by Teddy and directed by Kunihisa Sugishima, with Naohiro Fukushima handling series' composition, Hikaru Kodama designing the characters, and Keiji Inai returning to compose the series' music. It is set to premiere in April 2025.

Episodes

No.	Title	Directed by	Written by	Original air date
Special	"Special Program Just Before Broadcast" Transliteration: "Hōsō Chokuzen Tokuban" (Japanese: 放送直前特番)	Taku Sawada	N/A	April 4, 2021 (2021-04-04)
1	"I Maxed Out My Level" Transliteration: "Reberu Makkusu ni Natteita" (Japanese: レベルMAXになっていた)	Nobukage Kimura	Tatsuya Takahashi	April 10, 2021 (2021-04-10)
Aizawa Azusa has overworked herself to death at twenty-seven years old. A sympathetic Goddess reincarnates her as an immortal witch in a new world. Azusa is determined to live a peaceful life, building a farm in the mountains and hunting slimes every day to pass the time. Three hundred years has passed, and she becomes known as the Witch of the Highlands by the people of Flatta village due to her medicinal knowledge. On a whim, she has the adventurer’s guild measure her powers and finds the experience of killing multiple slimes every day for 300 years is equal to defeating 4380 dragons. She is now the strongest adventurer in the entire world. Soon, her carefree life is repeatedly interrupted by challengers, including Laika, a legendary dragon, who challenges her and is defeated, though she accidentally destroys Azusa’s house. Laika returns in the form of a young girl, hands over her treasure hoard to repair Azusa’s home, and asks to become Azusa’s pupil. Hoping it may make her life easier in the long run, Azusa accepts Laika as her pupil/maid, deciding to show her a little daily effort can go a long way, starting with building them a bigger house to live in.
2	"Along Came the Girl" Transliteration: "Musume ga Kita" (Japanese: 娘が来た)	Nanase Tomii	Yutaka Yasunaga	April 17, 2021 (2021-04-17)
Azusa is watched by a girl who swears revenge. Laika reveals attacks by villains and monsters are likely to increase now people know Azusa is strong, so they place a magic barrier around Flatta village. A child, Falfa, claims her sister, Shalsha (the girl from before), is trying to kill Azusa, and Azusa is their mother. Azusa learns the sisters are actually 50 year old Slime Spirits formed from the souls of every slime Azusa has killed. While Falfa considers Azusa their mother, Shalsha wants revenge for the slimes. Azusa’s magic is useless as Shalsha reveals she trained for fifty years to perfect her Smite Evil spell against Azusa. Laika protects Azusa and easily defeats Shalsha. Falfa explains Shalsha only trained Smite Evil to defeat Azusa, she is defenseless against everything else, and Shalsha will not be able to use it again for at least another fifty years. Forced to give up her grudge upon learning that Azusa is not the only one killing slimes and that the reason why people slay them is because they do not understand them, Shalsha decides to live happily. Azusa decides to become their mother and invites them to live with her. Shalsha agrees that Azusa can keep killing slimes, but only the white ones, which are evil. Azusa decides a life with a dragon pupil and slime daughters can be peaceful too.
3	"Along Came an Elf" Transliteration: "Erufu ga Kita" (Japanese: エルフが来た)	Ryūta Imaizumi Yoshiyuki Kumeda	Naohiro Fukushima	April 24, 2021 (2021-04-24)
Halkara, an elf girl, appears at Azusa’s home seeking help against the demon Beelzebub. She explains she created Nutri-Spirit, an energy drink, but it made Beelzebub ill, so she fled to avoid punishment. Azusa agrees to take Halkara as her student and puts a barrier around her house. While gathering mushrooms, Halkara carelessly eats one that has aphrodisiac effects and tries to seduce Azusa, who then punishes her. Azusa realizes Beelzebub, the Lord of Flies, has been in the house disguised as a housefly the whole time. Azusa challenges her to a duel, during which Beelzebub flies into the barrier and passes out from shock. Azusa helps her recover, during which Beelzebub explains the Nutri-spirit did not make her sick. It actually gave her the energy to work all night, but she overworked herself and made herself sick. Beelzebub actually wants more Nutri-spirit. Azusa punishes Halkara for wasting her time. Halkara decides to move her Nutri-spirit factory to Flatta to keep living with Azusa. Beelzebub agrees to visit again to settle her duel against Azusa in a friendly manner, and to visit Falfa and Shalsha. Azusa decides she can handle her new family growing even larger, until Laika suddenly announces she is returning to her own home.
4	"We Went to a Dragon's Wedding" Transliteration: "Doragon no Kekkonshiki ni Itta" (Japanese: ドラゴンの結婚式に行った)	Takahiro Ōkawa	Yutaka Yasunaga	May 1, 2021 (2021-05-01)
Laika clarifies she is only leaving temporarily to attend her older sister Leila’s wedding and they are all invited. Laika flies them to Mount Rokko, the volcanic home of the red dragons. Dragons from the enemy blue dragon clan crash the party led by Flatorte, a notorious bully who is jealous Laika’s sister is getting married before her, and so will use their ice breath to completely freeze Mount Rokko. Azusa decides not to interfere in an inter-clan issue, but when a dragon endangers her daughters, she defeats the blue dragons and forces Flatorte to flee the wedding. At Mount Rokko’s village, Azusa finds Beelzebub, there for a hot spring vacation, draining the rest of the blue dragon’s magic. Laika forces the captured Flatorte to assume her human form and pay for the damages. Azusa also forces her to sign a peace treaty so she can never attack the red dragons again. At the wedding, Flatorte begrudgingly wishes Leila well as a married woman. Laika asks Azusa if she can treat her as a sister now that her own sister is married. Azusa is happy that Laika is now her younger sister, Beelzebub as her older sister, and Halkara as her troublesome apprentice.
5	"A Ghost Appeared" Transliteration: "Yūrei ga Deta" (Japanese: 幽霊が出た)	Yasunori Gotō	Naohiro Fukushima	May 8, 2021 (2021-05-08)
Halkara’s new factory has a ghost, so she has been unable to hire workers. Azusa summons Beelzebub to help as she is scared of ghosts. Beelzebub forces the ghost to make itself visible, revealing she is a teenage girl called Rosalie who committed suicide centuries ago when her selfish parents sold her to be married to a cruel man. The factory used to be her family home and as a ghost, she is trapped in the place she died. Beelzebub reveals if she possesses a human to travel outside the building she will be freed, so Azusa offers Halkara as a convenient vessel, thrilling Rosalie. At Azusa’s home, Rosalie realises she is stuck in Halkara’s body, which Beelzebub explains could kill Halkara before long. Attempting to remove Rosalie proves difficult as she cannot be shaken out, exorcised out, or even scared out. Hoping putting Rosalie to sleep will help they get her drunk, allowing Halkara to regain her body, then Rosalie is sobered up by dunking Halkara in freezing water, causing Rosalie to jump out of Halkara’s body. Revealing she can use magic, Rosalie dispels the rumours about ghosts by making herself useful to the villagers, allowing Halkara to begin hiring workers.
6	"Along Came a Leviathan" Transliteration: "Rivaiasan ga Kita" (Japanese: リヴァイアサンが来た)	Kyōsuke Takada	Tatsuya Takahashi	May 15, 2021 (2021-05-15)
Beelzebub announces Azusa will receive the Demon Medal of Honour for ending the war between the dragon clans, meaning they must visit the Demon Realm. Rosalie worries she will not be able to wear a nice dress since ghosts are permanently stuck in the outfit they died in. Since no spell exists to change a ghost’s appearance, Azusa decides to create the spell herself and manages to successfully change Rosalie into a dress. Beelzebub arrives with a giant flying whale demon named Fatla to transport them to the Demon Realm. Fatla is so large she carries a luxury hotel on her back run by her sister Vania. After spending the night, they arrive at the demon capital city Vanzeld to meet the Demon King. The Demon King turns out to be a little girl, Provat Pecora Allieres, who is a fan of Azusa and Halkara’s Nutri-Spirit drink. Halkara, not initially realizing Provat is Demon King, makes several rude remarks and has to grovel for forgiveness. Provat finds her funny and forgives her, only for Halkara to accidentally head-butt her while rising from her groveling position. With Provat unconscious, Halkara is arrested for attacking Demon Royalty and sentenced to death.
7	"We Beat Up a Demon King" Transliteration: "Maō o Taoshichatta" (Japanese: 魔王を倒しちゃった)	Shinichi Omata	Tatsuya Takahashi	May 22, 2021 (2021-05-22)
Azusa hatches a plan to wake Provat using a foul tasting potion. However, she had to fight Provat's subjects due to them not trusting her. Provat wakes up and accuses Azusa of trying to poison her, then challenges her to a duel. Azusa destroys Provat’s sword, so Provat agrees to spare Halkara, but then admits she has been seeking someone stronger than her and declares Azusa is her big sister. Forced to agree, Azusa pretends to be a domineering big sister and forces Provat (now insisting on being called Pecora) to free Halkara after convincing her that her being knocked out was an accident. Pecora admits she has a “submission complex” and wants Azusa to boss her around. At the medal of honour ceremony, Pecora gives medals to Azusa and to Laika and Flatorte to celebrate the end of the dragon war. She also forces Flatorte to let Azusa touch her horns as a sign of peace. Flatorte reveals Azusa touching her horns means Azusa is now her master, so she must serve Azusa forever or commit suicide. Azusa realizes Pecora manipulated her into having to take Flatorte home with her, so she orders Flatorte to think and act for herself, freeing Flatorte from servitude through a loophole. Flatorte decides to live with her anyway and starts calling Azusa Mama, leading to sibling rivalry with Laika.
8	"A Fake Witch of the Highlands Appeared" Transliteration: "Kōgen no Majo no Nisemono ga Deta" (Japanese: 高原の魔女の偽物が出た)	Ryūta Yamamoto	Naohiro Fukushima	May 29, 2021 (2021-05-29)
Laika and Flatorte bicker constantly. Falfa and Shalsha believe they are grumpy from not having eaten fresh meat. Natalie from the guild brings news of a boar infestation, delighting Laika and Flatorte. Flatorte at first embrasses herself by taking her clothes off due to them being a hinderance. After killing the boars, Beelzebub and Fatla arrive and organize a feast of boar meat. Laika and Flatorte admit they were bickering over taking turns sleeping next to Azusa, so Azusa lets them both sleep in her bed. Azusa soon realizes someone has been impersonating her. While gathering information they stumble into a pub that specializes in serving masochists and the owner offers to identify fake Azusa if they spend time abusing her customers, which Azusa and Laika discover they have a talent for. The fake is an old woman who tries to flee, but is caught and transforms into a young witch named Eno. Eno explains she is a medicine maker and wants to be famous, but at the same time, does not want too many people to recognize her. Azusa suggests she sell her medicines, but in character as an idol girl so she will be both famous and completely anonymous. Her medicine proves to be so popular she asks Azusa’s advice on expanding her business, and Halkara even considers making her a business partner at her factory.
9	"My Daughter Turned Into a Slime and Couldn't Change Back" Transliteration: "Musume ga Suraimu Kara Modorenaku Natta" (Japanese: 娘がスライムから戻れなくなった)	Ryūta Imaizumi Yoshiyuki Kumeda	Yutaka Yasunaga	June 5, 2021 (2021-06-05)
Falfa somehow turns into a Slime and cannot turn back. Beelzebub suggests they ask Intelligent-Slime, who lives in Pecora’s castle. Intelligent-Slime does not know but points them to Magician-Slime atop a nearby mountain. Magician-Slime explains she was a slime, but used transformation magic to become human. She instantly diagnoses Falfa is in her “sleep form”, meaning she must have pulled a muscle in her sleep, making it too difficult to maintain a human form. As she did this on instinct, she must learn how to transform back and suggests asking Fighter-Slime, who gained her human form by studying martial arts. They locate Fighter-Slime at a fighting tournament, which Azusa and Beelzebub both enter. Beelzebub defeats Fighter-Slime, who helps Falfa turn back to human. Beelzebub demands Azusa fight her in the final to settle their old duel. Azusa refuses to lose while her daughters are watching and defeats Beelzebub again. Beelzebub later points out, having won the tournament, Azusa’s fame will spread further and cause her even more problems. Fighter-Slime asks to become Azusa’s student, but quickly reconsiders when she senses from Azusa’a aura how many slimes she has killed, so she becomes the student of the reluctant Beelzebub instead.
10	"A Minstrel Came to Town" Transliteration: "Gin'yū Shijin ga Kita" (Japanese: 吟遊詩人が来た)	Nanase Tomii	Yutaka Yasunaga	June 12, 2021 (2021-06-12)
Schifanoia, a rabbit-girl musician, visits Flatta village, but her Death Music does not impress the villagers. She passes out from hunger, so Azusa takes her home where she reveals her real name is Kuku. She has been failing as a musician for sixty-three years and is now considering getting a real job. Azusa advises she continue if it makes her happy. Flatorte, a music fan, points out Death Music is not popular anymore, plus Kuku is not that talented. Azusa suggests changing her style and asks everyone to think of new lyrics. Laika sings about devotion to Azusa, Halkara a song promoting her nutri-drink, Falfa and Shalsha sing about grasshoppers, and Rosalie sings about the depression of being dead. Kuku decides to abandon her Schifanoia persona and write a song inspired by Azusa and her family. Beelzebub arrives, hears Kuku’s new song and demands she perform at the demon music festival. Kuku suffers stage fright at the thought of such a large audience, but is helped through it by Flatorte, performing her song “Thank You” to massive applause. Her breakout performance leads to hundreds of offers to play at other concerts. Kuku thanks everyone for believing in her, especially Flatorte who tells her to keep playing whatever style makes her happy, no matter what.
11	"I Ate a Mushroom and Turned Into a Child" Transliteration: "Kinoko o Tabete Kodomo ni Natta" (Japanese: キノコを食べて子供になった)	Atsushi Kashiwa	Tatsuya Takahashi	June 19, 2021 (2021-06-19)
Halkara accidentally feeds Azusa a magical mushroom, turning Azusa into a child. Azusa is annoyed, but Laika and Flatorte are delighted. Azusa summons Beelzebub, who is unable to resist her cuteness, but agrees to take her to Pecora, who is also smitten with Azusa’s cuteness, but directs her to a dungeon within a giant World Tree where an alchemist lives. Azusa expects a dangerous journey, but finds the tree has been turned into a 108 floor tourist attraction where the higher they travel, the more money the tickets cost. Navigating the tourist traps takes time and they stay overnight in a hot spring on floor 38, then the next night on floor 84. Reaching floor 108, the alchemist, a young girl, gives her the cure, pills made by Eno. Eno arrives and is surprised Azusa climbed the tree when wyverns could have flown her to the top, plus, the medicine is available in Eno’s shop close to Azusa’s home. Azusa returns to Pecora’s castle and takes the pills, but forgets to change clothes first so when she grows her clothes tear and leave her naked, to Pecora’s delight. Tired and dirty, Azusa insists everyone bathe together, including Pecora, who asks if she can grope Azusa’s adult breasts, chasing her around the bathroom.
12	"We Opened a Coffee Shop" Transliteration: "Kissaten o Hiraita" (Japanese: 喫茶店を開いた)	Nobukage Kimura	Naohiro Fukushima	June 26, 2021 (2021-06-26)
The group visits Flatta which is preparing for the dance festival, a two-day event to celebrate the harvest. Azusa had previously distanced herself from past dance festivals, but having bonded with the others, wants to do something for the festival. During lunch at a cafe, Azusa gets inspiration from observing the strengths of others to run the coffee shop "The Witch's House" on the eve of the festival. In preparation for the festival, Azusa and the others try their waitress uniforms, prepare the menu, set up the coffee shop and distribute flyers to the Flatta townsfolk. On the eve of the festival, seeing the long queue to their coffee shop, Azusa opens the coffee shop one hour early and starts serving the customers with the others. As the coffee shop gets busier throughout the day, Beelzebub, Vania and Fatla and even Pecora pitch in to help, and Slime Fighter, Eno, and Kuku also visit the coffee shop. With their help, Azusa and the others manage to serve all the customers and close up shop. Azusa thanks the others for making the coffee shop a success before they take a break while she reflects on the events of the series. The next day, with the others wanting to visit the dance festival, Azusa decides to take the group to the dance festival on the night. Azusa gets a knock on the door which she opens, greeting the person which starts her day.

Reception

The light novel ranked ninth in 2019 in Takarajimasha's annual light novel guide book Kono Light Novel ga Sugoi! in the tankōbon category.

External links

• I've Been Killing Slimes for 300 Years and Maxed Out My Level
  • Official light novel website (in Japanese)
  • Official manga website (in Japanese)
  • Official anime website (in Japanese)
• Spin-off
  • Official spin-off manga "I Was a Bottom-Tier Bureaucrat for 1,500 Years, and the Demon King Made Me a Minister" website (in Japanese)
  • Official spin-off light novel "Red Dragon Women Academy" website (in Japanese)
  • Official spin-off manga "Red Dragon Women Academy" website (in Japanese)
• I've Been Killing Slimes for 300 Years and Maxed Out My Level (light novel) at Anime News Network's encyclopedia