How many movies have Hikaru Yamamoto and Riku Sanjou collaborated on?

They have worked on 6 movies together! Their first movie together was Kamen Rider × Kamen Rider W & Decade: Movie Wars 2010 (2009) while their highest rated movie together was Kamen Rider W Returns: Kamen Rider Eternal (2011). They have not worked together since Kamen Rider W Returns: Kamen Rider Eternal (2011). They are most known for their science fiction films together.