How many movies have Kappei Yamaguchi and Kouichi Nagano acted in together?

They have worked on 6 movies together! Their first movie together was One Piece Special: Open Upon the Great Sea! A Father's Huge, HUGE Dream! (2003) while their highest rated movie together was One Piece Episode of East Blue (2017). They have not worked together since One Piece Film Red (2022). They are most known for their action films together.