How many movies have Nobuhiro Arai and Souichirou Sako collaborated on?

They have worked on 4 movies together! Their first movie together was Naruto Shippuden the Movie: The Will of Fire (2009) while their highest rated movie together was Josee, the Tiger and the Fish (2020). They have not worked together since Josee, the Tiger and the Fish (2020). They are most known for their animation films together.