Hello! I'm looking for manga / anime / light novels in which a human (protagonist) changes into a non-human-creature and trades sides with them. I want the humans to be at war with these non-humans and preferably they don't make up with each-other, or get banished to an alternate realm; I want them to fight to the death til there's none of one side left. Kind of tired of the humans always succeeding one way or another... Gets on my nerves.

This is excluding cases where the enemies are not known, like your typical... Idk, vampire romance or something; where the existence of these beings are unknown to the general population. It must be an ALL OUT WAR! =3 (It can also progress from unknown to all out war though)

There is A-kun (17) no Sensou - I, the Tycoon?, but it was canceled and I heard the novels on which it was based are much better. The novels are untranslated and A-kun stays human even after siding with monsters.

Thank you

Shiki? http://www.mangaupdates.com/series.html?id=15089

The Anime is better though.

probably shiki, yes I agree. It's a horror manga with like 90% of the newly turned monsters siding with monsters. only read the manga though.

Idunno why but this manga.. looks alot like Accel World you should se that anime..
(haven't seen it) but they look extremly alike.

:REverSAL

Basic plot is that the main character gets transported to parallel dimension with various other people to participate in a game of killing zombies. Only she joins sides with the zombies, she just doesn't change into one

Shingeki no kyojin

Has a lot of the things your after in it, the all out war (between giants and humans) and the transformation of a character, also has people transforming and changing sides

Seiketsu no Haguruma

Its not a war between humans and non humans, but a war between red blooded humans and blue blooded humans in a fantasy world. The main character switches sides after learning what his war machines he made were doing to the other side

I approve with Shingeki no kyojin
to this point its not easy to predict whats gonna happen
in the beginning it was black/white (Humans Vs Giants)
now it get more and more foggy:

Inteligent Giants, Humans who turn to Giants, Walls that protect Humanity built by Giant, what looks like the ruling using giants to keep control, an insider destroying the walls ...etc

it looks like the character are about to have a paradigm shift when they are about to learn from a secret cabal a hidden truth will they see everything differently? and enemies will became allies and vis versa?

In MIYAZAKI Hayao's Nausicaä something even better happen
enemies became allies, sympathy with evil people, even the titular character love monsters more than humans and in the end

the gentle and self-rightious girl became morally ambiguous and cruelly cold and not stupidly cheap evil like some other dumb stories like to do

well its my own interpretation maybe other peoples will se things differently
but believe me its one of the most Epic and dark fantasies out there

Shiki

As far as I remember it's EVERYONE ELSE who sides with the monsters... Not the main character....

:REverSAL I'll definitely be reading this once it gets some more chapters out. The author seems to release them not-so-fast and I wouldn't want to wait half a year for another chapter to find out I don't remember anything about the story 🤢 ! Hang in there!
Shingeki no KyojinReading it and quite like the story 🙂 . Oh, I so hope the main character goes against the humans! Of course he wont, but, positive thinking :3.
Seiketsu no HagurumaReading this already too, but as far as I can tell it's just human species 1 vs human species 2, not any actual inhuman creatures unless you count the robots. Which rarely have anything to them.
NausicaäThis seems pretty interesting...

But does she actually side with the monsters and actively fight against the humans, or does she just simply like them more?

Thank you for your suggestions people! There's bound to be more :3!

Quote from wotonito

But does she actually side with the monsters and actively fight against the humans, or does she just simply like them more?

the short answer is

the humans are the real monsters

It's been many years since I've read that manga so i'm not sure about that
but think about it, the only manga made by Hayao Miyazaki and its different from his usual cheerful Animes or in another way its like Princess Mononoke up to Eleven 🤢

I'll have to disagree with Nausicaä.
She neither becomes a monster or sides with "monsters". She simply is/becomes a force of balance, on the side of life.
There definitely is a heavy moral lesson in there (if you're interested), and it's a good story nonetheless.

sorry if my post was understood as that
its better to not spoil the story
but the end was apocalyptic and her personality changed radically
I don't remember the end well
but the poster more interested in "how Evulz?" the main char is
I can understand that cause i have an "Evil woman" fetish 🤨

Actually it's just the opposite... IDEALLY the story has a human vs monster situation, however the main character, a human (preferrably female) originally on the side of humans, comes to find that the "monsters" are actually a lot less monstrous than the humans themselves are. So she eventually sides with the so-called "monsters" and helps wipe out the human race who cause much more suffering than they do.

So it's less how evil she is and more if she is willing to abandon her loyalty to her own kind and willing to side with those who are morally superior creatures. (Quite frankly I'm tired of humans always being seen as on the side of the "right" or "just")

What you wrote reminded me of Maoyuu Maou Yuusha - Kono Watashi no Mono Tonare, Yuusha yo Kotowaru. Probably not what the you had in mind, but oh well...

Edit: Fixed

Well... So far it looks like the ending is going to be ":3 Humans and Demons be friends!" Which is a nice ending and all but.... Bleh.

With that said I am enjoying the story though.