How many movies have Gou Koga and Toshio Furukawa collaborated on?

They have worked on 2 movies together! Their first movie together was One Piece Episode of Sabo: The Three Brothers' Bond - The Miraculous Reunion and the Inherited Will (2015) 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).