How many movies have Hidenori Arai and Mami Koyama collaborated on?

They have worked on 3 movies together! Their first movie together was Dr. Slump: Hoyoyo! Space Adventure (1982) while their highest rated movie together was Dragon Ball: Sleeping Princess in Devil's Castle (1987). They have not worked together since Dragon Ball: Sleeping Princess in Devil's Castle (1987). They are most known for their animation films together.