Based on the game by Anim.

Youko is satisfied. She lives a peaceful life with her husband, Masahiko, in addition to their son, Kazushi. But there is another thing she complains... They haven't had sex for some time. Eventually, an associate of Kazushi involves her house. His name is Ryouto. He or she is handsome and polite. But she doesn't know yet that Ryouto features a secret personality...