Meng de yi shang (1981)

Girl miss Lu is followed by Mr Sang one day because Lu looks like Sang's younger sister who suicided because her boyfriend Wan discarded her. Sang asks Lu to disguise herself as his sister and visit his grandma. Lu finds Wan is not such a bad man when Lu meets him later. She finds that Wan has singing talent, so she wants to encourage him to come out of the shadows.