Looking for the I’ve Been Killing Slimes for 300 Years manga reading order? This guide lays out the complete sequence — main manga, spin-offs by name, and where the light novels fit — so you can jump right in without second-guessing yourself.
The premise is simple and fun: an overworked woman dies and gets reincarnated into a fantasy world (a setup known in manga as “isekai,” meaning the character is transported to another world). She spends three centuries doing nothing but killing slimes, accidentally becomes the most powerful being around, and the rest is cozy comedy. The franchise has grown to include a light novel series (a short, illustrated Japanese novel format), a main manga adaptation, spin-off manga, and an anime — so having a clear roadmap helps.
I’ve Been Killing Slimes for 300 Years — Complete Manga Reading Order
Here’s the recommended reading sequence. Start with the main manga series, then branch out into the spin-offs — side stories that focus on supporting characters — once you’re familiar with the cast and world.
1. I’ve Been Killing Slimes for 300 Years and Maxed Out My Level (Main Manga)
This is your starting point. The main manga follows Azusa Aizawa, a former corporate worker who dies from overwork and is reincarnated into a fantasy world as an immortal witch. She spends 300 peaceful years killing low-level slimes near her cottage in the highlands, only to discover she’s accidentally reached the maximum level. What follows is a cozy, comedy-driven story as various characters — from dragon girls to demon lords — show up at her doorstep and become part of her ever-growing household, a group of unrelated characters who become as close as family.
The main manga currently has 16 volumes in English, published by Yen Press. The series is ongoing. Read the entire main manga series before moving to any spin-offs. Every supporting character who gets their own spin-off is introduced here first, and the humor and emotional beats land much better when you already know them.
I've Been Killing Slimes for 300 Years and Maxed Out My Level, Vol. 16
2. Spin-Off Manga — After the Main Series
Once you’ve read the main manga, you can explore the spin-off manga. These are separate series that shift the spotlight to supporting characters from the main story, exploring their backstories and side adventures in more depth. Here are the English-language spin-offs, all published by Yen Press:
- I Was a Bottom-Tier Bureaucrat for 1,500 Years, and the Demon King Made Me a Minister — Follows Beelzebub, the demon girl who spent 1,500 years as a low-ranking government clerk before being suddenly promoted to Minister by the demon king, in her own comedic adventures. 3 volumes in English.
- The Red Dragon Academy for Girls — A spin-off set at the school attended by the red dragon Laika, focusing on her side of the story. 2 volumes in English.
A few things to keep in mind about the spin-offs:
- They assume you already know who the characters are and how they relate to Azusa and her household.
- Reading them before the main manga will spoil character introductions, relationship dynamics, and certain story developments.
- They’re optional — the main manga tells a complete story on its own. But if you love a particular character and want more of them, the spin-offs deliver.
The spin-offs can generally be read in any order relative to each other, since they focus on different characters and don’t depend on one another. Just make sure the main manga comes first.
Why Reading Order Matters for This Series
You might be wondering whether order really matters for a lighthearted comedy series. It’s a fair question — this isn’t a dark fantasy saga with a twisting plot that falls apart if you read things out of sequence. But there are real reasons the main-series-first approach works best.
The franchise is layered. At its core, Killing Slimes for 300 Years started as a light novel series. The main manga adapts that source material — meaning it re-tells the light novel’s story in manga form, handled by a different creative team — condensing some multi-chapter storylines while faithfully capturing the tone and character dynamics. The spin-off manga then expand on individual characters who were introduced in the main story.
Spin-offs assume familiarity. Each spin-off manga centers on a character from Azusa’s household or wider circle — think of them as character-focused side stories. They don’t re-introduce these characters from scratch. If you pick up a spin-off cold, you’ll miss the context of why a character acts the way they do, what their relationship with Azusa means, and what makes certain callbacks funny.
Nothing breaks permanently. If you accidentally read a spin-off first, the series won’t become incomprehensible. The comedy still works, and the tone is forgiving. But you’ll get significantly more out of every spin-off chapter if you’ve already read the main manga. Character introductions, recurring jokes, and relationship dynamics all hit better with that foundation in place.
The main manga condenses the light novel. The manga adaptation streamlines certain storylines from the light novel. This means the manga moves at a slightly faster pace and focuses on the moments with the strongest visual comedy potential. For most readers — especially those starting with manga rather than novels — this is a plus.
Do You Need to Read the Light Novel First?
Short answer: no. The manga works perfectly well as your entry point into the series, and for most readers, it’s the best starting point.
Here’s how the light novel and manga relate to each other:
The Manga as a Standalone Entry Point
The main manga adapts the light novel’s story faithfully. You won’t miss critical plot points by reading the manga instead of — or before — the light novel. The manga captures Azusa’s personality, the comedy beats, and the gradual expansion of her household with strong visual storytelling that adds a lot to the experience.
For beginners especially, manga tends to be an easier and faster read than light novels. The art gives you immediate context for character designs, expressions, and action sequences that the light novel conveys through text alone.
When the Light Novel Adds Value
The light novel goes further ahead in the story than the manga. There are currently 19 light novel volumes available in English from Yen Press. If you catch up on all available manga volumes and want more, the light novel is where you continue. It also provides more world-building detail and internal monologue from Azusa that the manga condenses or skips.
Think of it this way: manga first for accessibility, light novel later for depth and continuation. Both are published in English by Yen Press, so switching between formats is seamless.
What About the Anime?
The anime adaptation has two seasons: Season 1 (aired April–June 2021) and Season 2 (aired April–June 2025). Together, they cover a wider range of the story than just the opening chapters. The anime can serve as an alternative starting point if you prefer watching to reading, though the manga still goes further in terms of overall story coverage.
A totally valid approach: watch the anime to see if you like the vibe, then switch to the manga for more story.
Which Edition to Buy — English Release Guide
Good news: the English release situation for Killing Slimes for 300 Years is refreshingly simple.
One Publisher, No Confusion
Yen Press is the sole English-language publisher for the entire franchise — the main manga, the spin-off manga, and the light novels. There are no competing translations, no “which version is better” debates, and no region-locked editions to worry about. If it says Yen Press on the cover (that’s the company name printed on the book’s spine), you’re getting the official English version.
Physical and Digital Options
All mainline manga volumes are available in both physical and digital formats. This applies to the light novels as well. Digital editions are available through platforms like Kindle and Kobo, and many public libraries carry the series digitally through services like Libby or Hoopla. Your choice comes down to personal preference:
| Format | Best For |
|---|---|
| Physical | Readers who like collecting volumes on a shelf, reading without a screen, and owning something tangible |
| Digital | Readers who want instant access, lower storage requirements, and the ability to read on a phone or tablet anywhere |
Both formats contain the same content — no bonus chapters or extras exclusive to one format over the other. You can find physical and digital volumes at major retailers like Amazon and Barnes & Noble, as well as through the Yen Press website.
Spin-Off Availability
The spin-off manga are also published in English by Yen Press in both physical and digital formats. When shopping for spin-offs, just double-check you’re grabbing the correct series title, since the spin-off names can look similar to the main series at a glance. The easiest way to tell them apart: the Beelzebub-centered spin-off is titled I Was a Bottom-Tier Bureaucrat for 1,500 Years, and the Demon King Made Me a Minister, while the other is The Red Dragon Academy for Girls.
A Note on Release Timing
English releases typically trail behind the Japanese publication schedule. This means the Japanese version may have volumes available that haven’t been translated yet. If you catch up on all available English volumes and find yourself waiting, that’s normal — Yen Press releases translations on a regular schedule, but there’s always some gap.
Check Yen Press’s release calendar or major retailer listings for the latest information on upcoming volumes.
Tips for First-Time Readers
Going into Killing Slimes for 300 Years for the first time? Here’s what to expect and how to get the most out of it.
Set Your Expectations for Tone
This is a comedy-driven, relaxed isekai — a story focused on peaceful daily life rather than intense battles. If you’re coming from action-heavy manga, you’ll want to adjust your expectations. There are no high-stakes battle storylines or world-ending threats here. The tension comes from comedic situations — like a dragon showing up to challenge Azusa and ending up moving in with her instead.
The appeal is warmth, humor, and watching a cast of lovable characters bounce off each other in increasingly ridiculous scenarios. Think of it as comfort food in manga form.
Episodic Structure Works in Your Favor
The story is largely episodic, meaning each chapter or short storyline tells its own self-contained comedic adventure. This makes it incredibly easy to read in short sittings. You can pick it up for one chapter before bed, enjoy a complete little story, and put it down without feeling like you’re abandoning a cliffhanger.
This structure also makes it a great change of pace if you’ve been reading something intense.
Why Main Series First (One More Time)
Every spin-off’s lead character — Beelzebub the demon girl, and others — gets their full introduction in the main manga. You’ll understand their quirks, their relationships with Azusa, and why their solo adventures are entertaining specifically because you already know them from the main series. This isn’t gatekeeping; it’s just how the stories were designed to be experienced.
Great for Manga Newcomers
If you’re new to manga or the isekai genre entirely, this series is a genuinely excellent starting point. It doesn’t require you to know genre conventions or tropes to enjoy it. The premise — overworked person gets a peaceful second life — is immediately relatable, and the comedy doesn’t rely on inside jokes about other series. You can come in completely fresh and have a great time.
Frequently Asked Questions
Is the Killing Slimes Manga Finished or Still Ongoing?
As of this writing, the I’ve Been Killing Slimes for 300 Years and Maxed Out My Level main manga is ongoing. There are 16 volumes available in English from Yen Press. English releases follow behind the Japanese schedule, so even after the Japanese serialization (where chapters are published in a magazine before being collected into volumes) wraps up, English volumes may continue releasing for some time after. For the latest volume announcements, Yen Press posts updates on their website.
Can I Start with One of the Spin-Off Manga?
It’s not recommended. The spin-off manga are written with the assumption that you already know the main cast. Character motivations, personality traits, and relationship dynamics are all established in the main series first. Starting with a spin-off would mean missing that context and potentially having character introductions from the main manga spoiled in a less impactful way.
Start with the main manga. If you love a particular character, the spin-offs will be waiting for you afterward.
How Does the Anime Fit into the Reading Order?
The anime has two seasons — Season 1 aired April–June 2021 and Season 2 aired April–June 2025 — and together they adapt a substantial portion of the story from the manga and light novels. If you’ve already watched both seasons, you can start the manga from volume 1 to get the full experience (the art and comedic timing add their own value), or you can skip ahead past the content the anime covered.
The manga goes further than the anime, so either way you’ll eventually reach new story material. And if you haven’t watched the anime at all, you don’t need to — the manga is a complete reading experience on its own.
Are All Volumes Available in English Yet?
English volumes from Yen Press may not have fully caught up with the Japanese releases. This is standard for translated manga — there’s always a gap between the Japanese and English publication schedules. Yen Press releases volumes on a regular cadence, so the English edition steadily closes that gap over time.
To check what’s currently available, look at the latest volume listings on major retailers. Yen Press also announces upcoming releases on their website, so you can see what’s coming next and when to expect it.
Is This Series Appropriate for Younger Readers?
Killing Slimes for 300 Years is a lighthearted comedy with no graphic violence, heavy fanservice, or dark themes. The humor is character-driven and family-friendly. It’s a comfortable recommendation for teens and adults alike, and it’s a particularly good pick for readers who want something cheerful and low-stress.