How many movies have Kyôtarô Nishimura and Masato Kai collaborated on?

They have worked on 6 movies together! Their first movie together was Murder on Raicho 9 (1987) and was their highest rated movie together. They have not worked together since Kyotaro Nishimura Travel Mystery 68: Disappearing Woman in Yamagata (2017). They are most known for their mystery films together.