幼馴染の彼女が、義理の兄と2人で暮らし始めた件について

Eri was a bright and popular girl with style and friends.
This story is about her.

Eri's neighbor was a boy two years older named Shogo.
They were good friends and over time became lovers.

One day Eri's parent got remarried, and she gained a new brother, Masao.
Masao was atrocious and cruel, making her his slave. Unlike sex with Shogo,
she felt no passion at all with him. But over time his force broke her...
and then she learned that she loved being mistreated.
In the end, her heart and body are surrendered fully to cruel Masao.