Onna no kappa

This movie is  a cross between a Japanese Pinku (softcore) and a musical.  In it,  Asuka, a 35-year-old woman  who works at a fish plant is engaged to her boss Taki.  One day while  she is walking by the lake near her work,  she encounters a legendary Japanese creature known as a kappa which has a human form but a beak face and a tortoiseshell back.  She soon realizes that the kappa is her old friend from school, Aoki,  who drowned when he was 17  but still loves her. As she hides Aoki from Taki and others, she must begin to decide what to do.

Note:  The International English Title for this movie  as set forth in IMDB  and Rotten Tomatoes and shown on the poster is “Underwater Love.”