This Boy Caught a Merman (2012)

After a near-drowning incident while searching for a lost photo, Shima is rescued by Isaki, a captivating merman. Their unexpected friendship blossoms, revealing a deep connection that defies their contrasting worlds. Yet, the challenges of love between a human and a mythical being complicate their relationship, testing their loyalty and courage. As Shima navigates the complexities of their bond, both must confront societal pressures and their own fears to find common ground.