The Stranger by the Shore Umibe no Étranger

After coming out to his parents, aspiring novelist Shun Hashimoto has no one to turn to, until the day he meets high schooler Mio Chibana on the beach. The two instantly click—just before Mio has to leave for the mainland. Now three years later, Mio returns with a confession. But after all this time, will Shun feel the same?

(Source: Funimation)