How many movies have Hideki Kakita and Ken Ootsuka collaborated on?

They have worked on 5 movies together! Their first movie together was Blue Gender: The Warrior (2002) while their highest rated movie together was Fullmetal Alchemist the Movie: Conqueror of Shamballa (2005). They have not worked together since Eureka: Eureka Seven Hi-Evolution (2021). They are most known for their animation films together.