Wasuresasete yo, Kouhai-kun.

A popular local belief claims that spotting a lucky dolphin can turn unrequited love into mutual affection. Natsume Shirahama dismisses this as a joke when a girl named Umika appears wearing a dolphin hair accessory. He initially assumes the trinket is unrelated, but Umika explains she came to see him again, hoping to rekindle a connection. Shirahama is still thinking of Hirose Haru, his former crush who left for university in Tokyo. As he spends time with Umika and assists her with schoolwork, he begins to feel a sense of nostalgia and fulfillment. Umika occasionally compares him to someone else from his past, suggesting she too is dealing with lingering feelings for an old love.