Keyakidai High School, three days before the graduation ceremony. Risako Mizuguchi, an English teacher popular with students, has been kidnapped, and Yoshiki Kurokawa receives a challenge letter from an unknown sender. "Solve the mystery of kidnapping. Only you can understand the truth." The same challenge was received by Junpei Ogyuda, who is a sports enthusiast in the soccer club, Mio Komatsu, a beautiful girl in the school's beauty pageant, and Kurokawa's childhood friend, one of the best talents, Ayane Takahata. The four were wondering why this member was gathered, but gradually another face of Mizuguchi became clear. And again, the students who were gathered had problems ... The youth mystery of young people who are sprinting and tied together with bonds.