How many movies have Mami Koyama and Sadafumi Sano collaborated on?

They have worked on 2 movies together! Their first movie together was Dr. Slump: Hoyoyo! Space Adventure (1982) while their highest rated movie together was Dr. Slump and Arale-chan: Hoyoyo! The Great Race Around The World (1983). They have not worked together since Dr. Slump and Arale-chan: Hoyoyo! The Great Race Around The World (1983).