Ever since they were young, Shun Asakura and Sana Wakatsuki have been the closest friends. Shun harbors romantic feelings for Sana, but when his family moves away in fourth grade, he never gets a chance to confess these feelings. For seven years, he lives with regret until he finally returns to Sana's town, determined to share his emotions with her. However, his plans get disrupted when he meets Ayumu Fujisaki, who looks exactly like him but is a better version of himself.