She is in love with him. She wants him. She'll do anything for him... learn to cook, wrap up pretty gifts, kill his enemies.
I want some manga like this, please. Can be shoujo or shounen or whatever, any genre, though I'd appreciate a twisted romance with a happy ending the most.
It doesn't really have to be that dark (as in: including murder).
Thanks in advance!

Koharu no Hibi. Because that is the manga for you.

Karakasa no Saien might be worth a look.

Yandere General

Mirai Nikki