How many movies have Keiko Yamamoto and Shuichi Ito collaborated on?

They have worked on 4 movies together! Their first movie together was Dr. Slump: Arale's Surprise Bang (1999) while their highest rated movie together was Interstella 5555: The 5tory of the 5ecret 5tar 5ystem (2003). They have not worked together since Yes! Precure 5: The Great Miracle Adventure in the Country of Mirrors (2007). They are most known for their animation films together.