How many movies have Masaharu Watanabe and Tatsuya Koyanagi collaborated on?

They have worked on 4 movies together! Their first movie together was Naruto Shippuden the Movie: The Lost Tower (2010) while their highest rated movie together was Road to Ninja: Naruto the Movie (2012). They have not worked together since Re:Zero - Starting Life in Another World Memory Snow (2018). They are most known for their animation films together.