Yosuga no sora

I fell in love with Nao Yorihime.

This anime is based on a Hentai PC game.
The story does not form continually but has various endings depending on the heroine.
It is a heartrending story but in any event, very Hentai.

Suddenly losing their parents, Haruka Kasugano and Sora Kasugano who are twins move to the country side surrounded by mountains.
Here, Haruka finds out who is the most important person in his life.

The story takes place in a small town called Okusome-Chou.  This town does not exist but it is said that Kabasaki-Chou in Tochigi-Prefecture is the model.