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

I've Been Killing Slimes for 300 Years and Maxed Out My Level anime series cover art
I’ve Been Killing Slimes for 300 Years and Maxed Out My Level

Series Overview

I’ve Been Killing Slimes for 300 Years and Maxed Out My Level (Slime Taoshite 300-nen, Shiranai Uchi ni Level Max ni Nattemashita / 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), also known as Slime 300, is a slice of life, fantasy anime that’s about exactly what the title describes.

At this point, I don’t actually remember how Azusa died in her old world (our world), but she’s given the opportunity to be reincarnated in another world and takes it. When she does so, she also requests that she be able to live a peaceful life forever — so she was made immortal.

For 300 years, Azusa lived out in the country by herself, killing the lowly slimes she came across and sometimes helping out the nearby villagers. Eventually, the villagers began to revere her as a god or protective spirit (on account of her immortality and maxed out level from killing slimes).

And, unfortunately for Azusa, this meant that her name and achievements were spread far and wide, leading to the end of her laid-back lifestyle.

Well, that’s not entirely correct. Azusa’s life is still largely easy-going even now. But the key difference is that she no longer has much peace and quiet on account of all the new friends she’s made and welcomed into her home as family.

The fact that Slime 300 is an isekai doesn’t really affect the series in any way. Even if you’re not a fan of the isekai sub-genre of fantasy, if you enjoy fantasy slice of life series, you’ll probably like this.

But, this isn’t the same as something like TenSura, which also involves slimes and some slice of life aspects. Slime 300 leans into slice of life way more than TenSura does.

Main Characters

There are actually a lot more characters in Slime 300 than I thought there were going to be at first. So in this section, I’m only going to cover the most important ones.

Azusa is the protagonist of the series and is a witch who’s maxed out her level exclusively via killing slimes. Due to the slime genocide she committed, Shalsha and Falfa were born. They’re physical manifestations of all the slime spirits released by Azusa, and she adopts them.

Another pair of main characters are Laika and Flatorte, who are red and blue dragons respectively. Laika is the first one to join Azusa’s family, with Flatorte being introduced later on in the series. These two have an intense rivalry.

Shalsha and Falfa from the anime series I've Been Killing Slimes for 300 Years and Maxed Out My Level
Shalsha and Falfa

Halkara is an elf who specializes in making various medicines. However, while her medicines are certainly effective, Halkara isn’t all that smart when it comes to anything else. And, it seems like she’s the cause of most of the issues Azusa eventually has to clean up.

Rosalie is the character I thought would be my favorite — until she was actually introduced. She’s a ghost girl who talks like a yankii, which, if I’m being honest, isn’t very cute.

And the last of the main characters I want to mention are two demons, Beelzebub and Pecora. Beelzebub’s most notable trait is that she’s a tanned anime girl. And Pecora is a loli demon lord, which is pretty par for the course as far as isekai go.

There is one more character who I want to mention despite her not being a main character. Fightie is my favorite character of the series. She’s a slime who specializes in martial arts and she’s perfect in every way.

Which Spring Season Isekai Featuring Aoi Yuuki is Better?

If you weren’t aware, Aoi Yuuki voiced the protagonist of two isekai anime that aired at the same time. Since I’m mentioning this in my Slime 300 review, you’ve probably already figured out that Azusa is one of them. The other is Kumoko from So I’m a Spider, So What? (which technically started airing in the winter).

Anyone who’s read my review of So I’m a Spider, So What? will probably have already guessed that Slime 300 is the better of the two anime. However, I do think the concept and story of So I’m a Spider, So What? are better.

Of course, since Slime 300 is a slice of life series, there’s not really a plot anyway, so it’s not competing in that regard. But in basically every other aspect, Slime 300 is the superior anime.

Pecora, Azusa, and Beelzebub from the anime series I've Been Killing Slimes for 300 Years and Maxed Out My Level
Pecora, Azusa, and Beelzebub

I’ve seen some other reviews of this series from people who really don’t seem to understand what it is. They complain that since nothing happens in it, there’s no point to it existing and that it’s therefore bad. I don’t see it that way at all.

I’m not going to say this is a great — or even good — anime. But I am going to say that it’s a slice of life comedy series and that it’s exactly what it advertises itself as. If you’re not into moe comedy, you’re obviously not going to like this.

At the same time, if you’re comparing every moe comedy series to something like Miss Kobayashi’s Dragon Maid, then sure, everything else is going to seem bad. Slime 300 isn’t setting out to revolutionize any of the genres it falls within.

It does the bare minimum to be a decent anime, and honestly, I think that’s all it needs to do. I’d much rather have that than the adaptation we got for So I’m a Spider, So What?


Overall, I’ve Been Killing Slimes for 300 Years and Maxed Out My Level is a 6/10. It’s fine for what it is. It’s not particularly good, but it’s better than what I would call completely average. With a bit more animation and maybe some better scenarios for the characters to interact within, it could have been a 7.

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