How many movies have Nakamatsu Toshihiro and Shōji Sakai collaborated on?

They have worked on 9 movies together! Their first movie together was Eizu o buttobase: Momoiro puttsun musume (1987) while their highest rated movie together was Welcome to the Ogenki Clinic: Feel Good All Over Again (1988). They have not worked together since Groper Train: Oral Attack (1989).