How many movies have Kinji Fukasaku and Sonny Chiba collaborated on?

They have worked on 21 movies together! Their first movie together was Drifting Detective: Tragedy in the Red Valley (1961) while their highest rated movie together was Battles Without Honor and Humanity: Deadly Fight in Hiroshima (1973). They have not worked together since Battle Royale II: Requiem (2003). They are most known for their action films together.