The honban: Fûfu seikatsu-hen (1985)

Sinopsis

Apartment for newlyweds. Sachiko lives with her husband, Tadao Yamanaka who works at an advertising agency. A film crew consisting of Tetsuo and Mami arrives to film the innocent couple, who have yet to discover their sexual passion. At first, the Yamanakas are confused, but they gradually become more excited, and eventually get lost in each other , ignoring the director's instructions.