How many movies have Ikuyo Koyauchi and Shōji Sakai collaborated on?

They have worked on 3 movies together! Their first movie together was Shiyôzumi sei-shitagi (1995) while their highest rated movie together was Kyōkai-sen no mukō-gawa (1998). They have not worked together since YADO: Tsukiyono-mura Yamanba Densetsu (2002).