Two individuals grappling with the loss of their loved ones are in for a surprise during their seaside getaway. A mystical figure named "Umi Warabe" may be just what they need to heal their wounds and make progress with their lives. During a summer excursion, high schoolers are led by Matsunaga Yoshihiro to the beach. One fateful evening, he rescues Morisawa Nao, a student who was attempting to drown herself. Nao had been to the same location the previous year with her fiancé who later died in a plane crash. As they grow closer, Yoshihiro's own painful history is revealed. Throughout it all, a young enigmatic girl seems to watch over them and appears when it matters most.