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

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 (Slime Taoshite 300-nen, Shiranai Uchi ni Level Max ni Nattemashita)

6.9(222,301)

MAL Score

Ranked #5531

Popularity #590

Comedy
Fantasy
Isekai
CGDCT

Episodes: 12
Duration: 23 min per ep
Aired: Apr 10, 2021 to Jun 26, 2021
Status: Finished Airing

Synopsis

After working herself to death in the corporate world, Azusa Aizawa awakens before a goddess who grants her immortality and a quiet second life in a fantasy realm. Determined to avoid stress, she settles into a gentle routine: farming, helping protect a nearby village, and casually defeating around 25 slimes a day—an easy, steady habit she keeps up for three hundred years.

That peaceful monotony cracks when Azusa discovers she’s somehow reached level 99, the world’s maximum, purely from slimes. Hoping to keep her laid-back life intact, she tries to stay out of the spotlight, but word of her power spreads anyway. Visitors begin arriving at her home, including the dragon Laika and the elf Halkara—some eager to test her strength, others seeking help—and Azusa’s solitary days gradually give way to a growing circle of companions who start to feel like family.

Otaku Consensus

Revoroot’s 12-episode adaptation succeeds by letting Nobukage Kimura’s direction privilege calm comic timing, household routines, and character chemistry over escalation. Critics and fans broadly read it as a purpose-built comfort isekai in the BOFURI-adjacent lane, with the main complaint being just as consistent: the stories stay shallow, with little danger, plotting, or dramatic consequence for viewers who need momentum.

Why You Should Watch

Watch this if you want an isekai that removes the grind, the harem arms race, and the apocalyptic quest marker, then replaces them with female-led domestic comedy. It scratches the same low-stress itch as BOFURI, but it is even less interested in combat spectacle; the payoff is in how a mostly female cast turns fantasy archetypes into found-family sitcom energy. The AniList tag profile tells you exactly what lane it owns: Found Family at 98%, Family Life at 94%, Witch at 93%, and Iyashikei at 88%. If your ideal fantasy watch is rural, cute, and conflict-light without becoming pure background noise, this is a clean 12-episode palate cleanser with enough running gags and magical-community texture to feel authored rather than algorithmically cozy.

Key Characters

A
Azusa Aizawa(VA: Aoi Yuuki)
Azusa is the rare overpowered isekai lead whose fantasy is not domination but boundary-setting, making her strength funniest when it protects her right to live slowly.
L
Laika(VA: Kaede Hondo)
Laika gives the ensemble its earnest disciple energy, turning dragon pride into a source of deadpan comedy and household discipline.
H
Halkara(VA: Sayaka Senbongi)
Halkara is the show’s chaos catalyst, the elf whose business-minded confidence and mistake-prone timing keep the slice-of-life format from becoming too placid.

What Makes It Stand Out

1
The series is structurally closer to iyashikei sitcom than quest fantasy: most episodes prioritize visitors, domestic routines, and social friction instead of villains or dungeon progression.
2
Revoroot’s production favors soft character acting and clean fantasy-color design over action set pieces, which matches the review consensus that the show is made for relaxation rather than spectacle.
3
The AniList tag spread is unusually decisive for a modern isekai: Primarily Female Cast is listed at 99%, Found Family at 98%, Family Life at 94%, and Cute Girls Doing Cute Things at 90%, making its appeal more specific than the broad genre label suggests.
4
Tatsuya Takahashi’s series composition keeps the adaptation in a low-stakes rhythm, using short-form social problems and comedic interruptions rather than a single season-long danger arc.
5
Its public reception sits in the comfortable-middle zone: a 6.88 MAL score from 220,692 votes and an AniList score of 68/100 indicate a widely sampled title appreciated for mood more than ambition.

Fun Facts & Trivia

Fun fact 1: The anime aired as a completed 12-episode Spring 2021 TV run, from April 10 to June 26, 2021, with Revoroot as the animation studio.
Fun fact 2: Kisetsu Morita is credited for the original story, while Benio provided the original character designs that Keisuke Gotou adapted for animation.
Fun fact 3: The visual staff credits are unusually granular in the available data: Emi Honda handled sub-character design, Atsushi Kashiwa handled prop design, and Nachi Kio is specifically credited for the title logo design.
Fun fact 4: Ken Naitou served as art director with Chihiro Ido on art design, a staff split that helps explain the show’s emphasis on readable rural spaces and cozy fantasy interiors.
Fun fact 5: Despite its modest MAL rank of #5503, the series reached MAL popularity rank #591 and has 2,436 AniList favourites, showing that its niche comfort appeal translated into broad visibility.