How many movies have Hachirō Kai and Osamu Onodera collaborated on?

They have worked on 8 movies together! Their first movie together was Uno Kôichirô no uwaki nikki (1980) while their highest rated movie together was Female Teacher: Dirty Afternoon (1981). They have not worked together since Young Girls' Holding Cell (1982). They are most known for their drama films together.