How many movies have Chikao Ohtsuka and Yoshio Urasawa collaborated on?

They have worked on 2 movies together! Their first movie together was Lupin the Third: The Legend of the Gold of Babylon (1985) and was their highest rated movie together. They have not worked together since Nintama Rantarou Movie: Ninjutsu Gakuen Zenin Shutsudou! no Dan (2011).