Nikuen

It is an anime adaptation of the manga of Eda.

The main character recently started dating a girl named Aoi. One day, she invited her to her home. However, when he goes there, Aoi’s mother has sex with a stranger. The next day when Aoi returns home after school, she sees the same man again, who this time introduces herself to her and shows her her phone. But before she can react, Aoi loses control of her body.