How many movies have Gou Koga and Kazuya Nakai collaborated on?

They have worked on 3 movies together! Their first movie together was One Piece: Clockwork Island Adventure (2001) while their highest rated movie together was The Birth of Kitaro: The Mystery of GeGeGe (2023). They have not worked together since The Birth of Kitaro: The Mystery of GeGeGe (2023). They are most known for their animation films together.