How many movies have Tsutomu Shibayama and Yoshimasa Iiyama collaborated on?

They have worked on 16 movies together! Their first movie together was Doraemon: Nobita and the Castle of the Undersea Devil (1983) while their highest rated movie together was Doraemon: Nobita and the Galaxy Super-express (1996). They have not worked together since Doraemon: Nobita and the Legend of the Sun King (2000). They are most known for their family films together.