How many movies have Kaori Saito and Kyoko Kotani collaborated on?

They have worked on 4 movies together! Their first movie together was Eden of the East Movie I: The King of Eden (2009) 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 Hula Fulla Dance (2021). They are most known for their animation films together.