Three years ago in Minami-Atami, Japan, a school bus carries four female high school students to an entrance ceremony. The bus driver named Ayumu Hirasaka (Masato Hagiwara) suddenly stops the bus when he spots an old man collapsed on the road. The bus driver gets out to check on the man leaving the four high school students on the bus. Suddenly, the bus starts to go down a slope, even though the bus driver enabled the emergency brakes. The bus driver chases after the falling bus, but it disappears into the woods.
As soon as the case is reported to the police station, Osamu Sizu (Yutaka Matsushige) leaves for the accident scene. When he arrives he spots the bus driver running in the woods. No clues are to be found.
Three days later, late at night, Mai Shinnome (Ayaka Miyoshi) is found unconscious at a downtown bus stop. She is sent to the hospital, still unconscious, and the other three girls are still missing.
Three years later, Mai Shinnome finally regains consciousness. National investigators Kenzo Hoshizaki (Joe Odagiri) & Sae Kitajima (Chiaki Kuriyama) are sent out to Minami-Atami to interview her and uncover the truth of their disappearance.