Manga Oni ga Deru ka Ja ga Deru ka / Out Comes the Devil. Out Comes the Snake.
When our hero, Matsubara Yuu, suddenly finds himself moving back to his mother's home, a number of strange things happen to him. He meets Suzu, a beautiful girl who falls in love with him at once, even wanting to have his children. Even if he wanted to run away from the situation, his way was blocked by a huge cow attacking him. In fact, in all of these, he seems to be the cause!