Ride Your Wave (2019)

Hinako is a surf-loving college student who has just moved to a small seaside town. When a sudden fire breaks out at her apartment building, she is rescued by Minato, a handsome firefighter, and the two soon fall in love. Just as they become inseparable, Minato loses his life in an accident at sea. Hinako is so distraught that she can no longer even look at the ocean, but one day she sings a song that reminds her of their time together, and Minato appears in the water. From then on, she can summon him in any watery surface as soon as she sings their song, but can the two really remain together forever? And what is the real reason for Minato’s sudden reappearance?

Source: TMDb