How many movies have Hachirō Kai and Ryoichi Kusanagi collaborated on?

They have worked on 7 movies together! Their first movie together was Sukeban mafia: Chijoku (1980) while their highest rated movie together was Wife's Sexual Fantasy: Before Husband's Eyes (1980). They have not worked together since Woman in Black Lingerie (1982). They are most known for their drama films together.