Makimura Koutarou decides to confess his feelings to the aloof Serizawa Kaho during summer break. However, a chance meeting with a mysterious girl the night before catapults him into the future. In this future, he discovers that Kaho is not only his girlfriend but has also met a tragic end. Determined to alter this fate, Koutarou travels back to his present time to alter destiny and rescue his beloved.