Itoshi no Betty Mamonogatari

A devil-girl with the face of an angel and a heart of gold, blond Betty falls in love with an earthbound gangster, Danpei Kimogawa, when they meet in a rainstorm. They end up living together in a Tokyo highrise apartment, though Danpei has trouble coping with his new witch and demon in-laws dropping in at inopportune moments. Betty has actually been sent to the human world on a mission to defeat the demon Lutan. While Betty continues her task, her skeletal grandmother sends nubile nymphs to tempt Danpei and see if he is suitable husband material. (Source: The Anime Encyclopedia)