How many movies have Hachirō Kai and Hitoshi Takagi collaborated on?

They have worked on 4 movies together! Their first movie together was Uno Koichiro no Shûdôin Fuzoku Joshi-ryô (1981) while their highest rated movie together was Uno Koichiro no Hiraite Utsushite (1981). They have not worked together since Horny Working Girl: From 5 to 9 (1982).