Cloistered Nun: Runa's Confession

Cloistered Nun: Runa's Confession (1976) is a Japanese pink film in the nunsploitation genre starring pop singer Luna Takamura, directed by Masaru Konuma and produced by Nikkatsu. AllRovi reports of the film, "As Konuma is not one to pull political punches for the sake of lightweight erotic fluff, the film is far more pointed than the numerous European 'sexy nun' films it ostensibly resembles." Jasper Sharp calls it "a typically profane offering in the most peculiar of Nikkatsu's pornographic subgenres".

Synopsis from Wikipedia, CC BY-SA 4.0. Everything below written here.