Konta, once a promising swimmer, saved a young girl from drowning in the sea. Though she survived, she fell into a coma. Consumed by guilt, Konta abandoned the sport entirely.

Five years later, he has become a recluse — a shadow of his former self. Worried for his future, his older sister invites him to coach the powerhouse swimming team at Shikinomori High School. Reluctantly, he headed to the pool — and there he met the very girl he had saved many years ago...