How many movies have Keiko Nakaji and Yoshinobu Michihata collaborated on?

They have worked on 6 movies together! Their first movie together was Case Closed: The Fourteenth Target (1998) while their highest rated movie together was Go! Anpanman: Tears of the Mermaid Princess (2000). They have not worked together since The Piano Forest (2007). They are most known for their animation films together.