Mitsuru Aomi and Koichi Yamada are 17 years old and classmates. They are opposites in personality and are strongly attracted to each other. One winter morning, Koichi is hit by a truck. Koichi stands up with a nonchalant look on his face, even though he must have been hit hard on the head. There is no pulse or heartbeat, but Koichi is certainly “alive” and smiling as usual. Mitsuru accepts this contradiction. However, his classmates gradually begin to forget Koichi’s existence…