How many movies have Hiroshi Butsuda and Keiji Kameyama collaborated on?

They have worked on 8 movies together! Their first movie together was Kamen Rider Hibiki The Movie: Hibiki & The Seven War Oni (2005) while their highest rated movie together was Farewell Kamen Rider Den-O: Final Countdown (2008). They have not worked together since Kamen Rider Decade: All Riders vs. Dai-Shocker (2009). They are most known for their science fiction films together.