How many movies have Naoki Osada and Toshihiko Seki collaborated on?

They have worked on 2 movies together! Their first movie together was Kamen Rider Kiva: King of the Infernal Castle (2008) and was their highest rated movie together. They have not worked together since Heisei Rider vs. Showa Rider: Kamen Rider Wars feat. Super Sentai (2014).