How many movies have Kazuo Koike and Tomisaburō Wakayama collaborated on?

They have worked on 8 movies together! Their first movie together was Lone Wolf and Cub: Sword of Vengeance (1972) and was their highest rated movie together. They have not worked together since Lone Wolf & Child: Assassin on the Road to Hell (1989). They are most known for their action films together.