Natsuo has a crush on his high school teacher, Hina and to get past his feelings he goes on a group date and meets Rui, who he sleeps with, but things become more complicated when he finds that they will both become step-sisters.
Rui has transferred to Natsuo's school and they opt to act like strangers, but at lunch Natsuo stages an argument, which helps Rui make friends because their classmates get to see her personality.
Natsuo asks Hina to end her relationship, but she refuses and then Natsuo and Rui come up with a plan.
After Natsuo and Rui create trouble for Hina and Shuu, Hina ends the relationship and follows Natsuo to his mothers grave.
Momo meets Natsuo and falls for him, but Natsuo doesn't think it's a good idea for them to date because she is emotionally dependant upon him.
After borrowing a book from the library, Natsuo learns the lesson of crime and punishment. However, the punishment doesn't always fit the crime.
Taku Yashiro
Voice
Maaya Uchida
Yōko Hikasa
Haruka Yoshimura
Konomi Kohara
