How many movies have Hiroyoshi Iida and Mamiko Nakanishi collaborated on?

They have worked on 6 movies together! Their first movie together was Naruto Shippuden the Movie (2007) 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 Yo-kai Watch: Forever Friends (2018). They are most known for their animation films together.