Shiosai (1971)

Lonely youth Shinji meets Hatsue, a pretty pearl diver, on the beach and the two fall in love. But Shinji has a rival for Hatsue's affections, Yasuo. Yasuo spreads unpleasant gossip about his rival, and Hatsue's father forbids her to see Shinji. But when the boy saves the passengers on a boat owned by Hatsue's father, his luck in love begins to change.