I've read the novel and saw the anime. When I found out the manga existed as well I was very happy but... How can I say it?

It's horrible. It is so bad I wish I never read it. The novel is dark, deep, it makes you think about life as a whole.
The anime is very similar to the novel, althought the animations are not always top tier it follows the story without changing anything.

And then there is the manga. Characters changed so much I can barely recognize them. The main protagonist wears bitchy chlotes almost all the time and the whole plot is blown away to introduce more yuri sex than needed.

In the original work sex is important to understand the society they created, in the manga it is just mere fanservice, a way to show some boobs when NOT NEEDED. And I like boobs.

Horrible.