Lumen Lunae

There is a rumor around school about Houjyou Aika giving birth to a child at the age of fifteen, just now returning to school about a year later. Reality is far worse than the gossip. Aika was raped by the demon ruler (Suruga) and she somehow survived long enough to give birth to a boy. The half-demon was taken to the 'real world' (aka demon world) by his father and imprisoned in the "Cliff of Time". During his time there, Kai was a plaything to his elder brother, Kaiga.

This is a serious series with rather violent, bloody scenes. The demons have no morals, seeing the human world as a big playground and sex with anyone is just fine. The only mistake Kai made in his life was existing, and he is constantly punished for it.