Koshiro and Nanoka, two young people both recovering from heartbreak, meet and develop a mutual attraction towards each other... until Koshiro's father informs him Nanoka is his daughter, and thus Koshiro's sister.
Koshiro struggles with his feelings for Nanoka, when she comes to his office he snaps and yells at her, enraging her and making her go out with her friends away from home.
Koshiro bumps into his ex-girlfriend Shoko, but she has moved on with a new man. A frustrated Koshiro finally faces the fact that he is attracted to Nanoka.
Koshiro looks back on his early years, when he and Nanoka were innocent children and their parents were still married. He resolves to be the best brother for Nanoka.
Nanoka comes to Koshiro's office, and his workmate Kaname says they make a nice couple. Later, Nanoka declares her love to Koshiro, but he angrily brushes her off.
