How many movies have Koichi Usami and Kouji Matsuyama collaborated on?

They have worked on 2 movies together! Their first movie together was The Demonic Beast Front (1990) while their highest rated movie together was Donten: Laughing Under the Clouds - Gaiden: Chapter 2 - The Tragedy of Fuuma Ninja Tribe (2018). They have not worked together since Donten: Laughing Under the Clouds - Gaiden: Chapter 2 - The Tragedy of Fuuma Ninja Tribe (2018).