How many movies have Akio Watanabe and Nisio Isin collaborated on?

They have worked on 4 movies together! Their first movie together was Kizumonogatari Part 1: Tekketsu (2016) while their highest rated movie together was KIZUMONOGATARI -Koyomi Vamp- (2024). They have not worked together since KIZUMONOGATARI -Koyomi Vamp- (2024). They are most known for their mystery films together.