How many movies have Ken Kobayashi and Yoshikazu Sakata collaborated on?

They have worked on 2 movies together! Their first movie together was Investigative Notes of a Taxi Driver: The Black Sunflower Woman (1998) while their highest rated movie together was Taxi Driver's Mystery Diary 37 - Mystery of Double Homicides from Tokyo to Hamamatsu (2015). They have not worked together since Taxi Driver's Mystery Diary 37 - Mystery of Double Homicides from Tokyo to Hamamatsu (2015).