2025年春アニメ

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～そのに～

テディー異世界スローライフほのぼの 2025年4月5日〜6月21日（第2期・全12話）

Azusa Aizawa, an ordinary office worker who died from overwork, is reincarnated by a goddess as the immortal witch Azusa. Wanting a slow, relaxed life this time around, she spends 300 years casually defeating slimes for pocket money in her remote highland home. Before she knows it, she's become the strongest being in the world — and word spreads, drawing dragon girls, slime spirits, elves, and ghosts to her door, each with their own troubles she can't ignore. Azusa welcomes them all in as family. Season 2, subtitled 'Sononi,' began airing in April 2025.

📝 Highlights

👥 Characters

💫 Foreshadowing & Quotes

❓ FAQ

🌟 Featured Comments

📝 Highlights & Appeal Light spoilers

01① The highland home grows livelier than ever

Following Season 1, even more colorful girls gather at Azusa's highland home.

02② A trip to the Red Dragon's homeland

The family visits Laika's homeland among the Red Dragons, among other outing episodes.

03③ Exploring the World Tree dungeon

A highlight is the family's challenge of the massive dungeon known as the World Tree.

04④ More spirit characters join the cast

New spirit characters like the dripping spirit Yufufu and the pine spirit Misujantī add color to the story.

05⑤ The cost of 300 years to becoming the strongest

Azusa just wants a quiet life, but her absurd strength keeps dragging her into chaos — the core comedy engine of the show.

06⑥ Gentle animation from Teddy

Warm, gentle everyday scenes are drawn with care, in a relaxed pace and comforting art style.

07⑦ OP theme 'So☆Lucky' by Yui Ogura

The bright opening theme, sung by Yui Ogura (who voices Sandra), lightly colors the family's everyday life.

08⑧ ED theme 'Eeny Meeny Manimo' by Aguri Onishi

The calm, soothing ending theme wraps up each episode's warm afterglow.

💡 Key Points & Predictions Some spoilers

As Azusa's world expands to places like the Red Dragon homeland and the World Tree dungeon, the biggest point to watch is which new girls will join her family next.

Tap to reveal

🧾 Story So Far Contains spoilers

The immortal witch Azusa becomes the strongest being in the world after 300 years of casually defeating slimes. In Season 1, colorful girls like Laika, Falfa, Shalsha, and Halkara joined her highland home one after another. Season 2, 'Sononi,' depicts episodes that deepen the family's bonds further, including a visit to the Red Dragon homeland and a challenge at the World Tree dungeon.

Tap to reveal spoiler

✅ Recommended Viewing Points

Recommended for those who want warm, family-like slice-of-life over battles, and for fans of slow-life stories featuring an absurdly overpowered protagonist just trying to relax.

👀 Trivia & Fun Facts

The original light novel is by Kisetsu Morita, published under SB Creative's GA Novel imprint. Season 1 aired from April to June 2021, and Season 2, 'Sononi,' arrived five years later, starting in April 2025.

Azusa Aizawa (CV: Aoi Yuki)

A former office worker reincarnated as an immortal witch after dying from overwork. 300 years of defeating slimes made her the strongest being alive.

Laika (CV: Kaede Hondo)

Daughter of the Red Dragons, who became Azusa's earnest, ambitious disciple after losing to her in battle.

Falfa (CV: Ayaka Senbongi)

A slime spirit (the elder sister) born from the souls of slimes Azusa defeated. Bright and cheerful by nature.

Shalsha (CV: Minami Tanaka)

The younger sister among the slime spirits, introverted and quiet, with a love of history and theology.

Halkara (CV: Ayaka Harada)

An elf apothecary and businesswoman over 200 years old, who runs a pharmaceutical company built on her own 'nutrition sake.'

Rosalie (CV: Riho Sugiyama)

A ghost girl who died by her own hand at 15, two centuries ago. She wields telekinesis and has a strong sense of loyalty.

Flatorte (CV: Azumi Waki)

Daughter of the Blue Dragons, wielding icy power. Over 400 years old, but rather brawn-over-brains.

Sandra (CV: Yui Ogura)

A mandragora girl over 300 years old who gained sentience. Has a somewhat tsundere personality.

Beelzebub (CV: Manami Numakura)

The Fly King, serving as the demon realm's agriculture minister. About 3000 years old, and a devoted fan of Azusa's nutrition sake.

Pecora (CV: Yukari Tamura)

The demon nation's ruler, who looks like a middle schooler. She adoringly calls Azusa 'big sister.'

💫 Unresolved Foreshadowing Contains spoilers

・How many more spirits and new girls will end up joining Azusa's highland home?
・What new chaos will Azusa's absurd strength attract next?
・What lies deep within the World Tree dungeon?

Tap to reveal spoiler

💌 Predicted Viral Quotes for Next Season

The show's laid-back narration — matching its title's premise of 'somehow ending up at max level' — is the comedic backbone of the whole series.
The scenes of Pecora adoringly calling Azusa 'big sister' are heartwarming moments where even the overpowered witch gets swept along.

What kind of anime is “I've Been Killing Slimes for 300 Years Season 2 Guide”?

What are the theme songs (OP/ED) of “I've Been Killing Slimes for 300 Years Season 2 Guide”?

You can find the theme songs of “I've Been Killing Slimes for 300 Years Season 2 Guide” ranked by view count in the anime song ranking on the homepage. Each song’s page also shows a chart of its view-count history.

How can I rate or comment on “I've Been Killing Slimes for 300 Years Season 2 Guide”?

Use the rating section on the left (PC) or top (mobile) to give a star rating (out of 10) or a like. You can also share your thoughts in the comment box at the bottom of the page. A nickname is optional.

🗨 高原の家住民推し ❤ 489

I love how much livelier the highland home has gotten in Season 2.

🗨 アズサ最強勢 ❤ 456

The gap between Azusa just wanting to relax and being the strongest in the world is perfect.

🗨 ライカ推し ❤ 423

Laika's earnest dedication as a disciple heals me every episode.

🗨 精霊姉妹ファン ❤ 398

The Falfa and Shalsha sister duo is just too precious.

🗨 ペコラ推し ❤ 376

Pecora adoring Azusa is so wholesome, I can't get enough.

🗨 OP大好き勢 ❤ 354

Yui Ogura's So☆Lucky is so upbeat, it gives me energy every episode.

🗨 5年待った勢 ❤ 332

Season 2 after five years of waiting was absolutely worth it.

🗨 世界樹ダンジョン勢 ❤ 309

The World Tree dungeon episode had a great sense of scale.

🗨 ハルカラ社長推し ❤ 287

Halkara's knack for causing trouble makes for the best comedy.

🗨 ED余韻好き ❤ 265

Aguri Onishi's Eeny Meeny Manimo is the perfect way to close out every episode.

💬 Comments

タイトル	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～そのに～
原作	森田季節（SBクリエイティブ GAノベル）
制作	テディー
放送時期	2025年4月5日(土)〜6月21日（第2期・全12話）
放送局	TOKYO MX・AT-Xほか
OP主題歌	「So☆Lucky」小倉唯
ED主題歌	「イニミニマニモ」大西亜玖璃
ジャンル	異世界、スローライフ、ほのぼの
公式サイト	slime300-anime.com

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 ～そのに～