One day after school, he discovers and steals the gym clothes of Nanako Saeki, the girl he has a crush on. However, he learns that Sawa Nakamura, a girl he loathes, happens to catch him in the act. Nakamura blackmails Kasuga into a "contract," or else she will reveal his secret.
The manga is by Shuzo Oshimi, which is published by Kodansha and around the 6th volume. The anime's director will be Shiroshi Nagahama of Mushishi and Detroit Metal City fame. IT has been defined as a corrupt love story.