Tonight, Natsuo lost his virginity. His partner? His name is Rui and you've just met him through friends at school. She was the only one who engineered this situation, saying she just wanted to learn more about sex. She didn't want to start a relationship, she doesn't care about Natsuo. However, Natsuo doesn't feel right about losing his virginity to a girl he doesn't necessarily like. In fact, it made him feel like he was betraying his school crush: teacher Hina. A love triangle arises between Natsuo, Rui and Hina and it all ends up with them in the same family!