Pink film ピンク映画
Japanese independent sex films (pinku eiga), made fast and cheap since the early 1960s; the related Nikkatsu Roman Porno line developed an S&M subgenre from 1974.
Pink film, pinku eiga in Japanese, names films from independent studios that contain nudity or deal with sexual content. Wikipedia, drawing on Weisser’s Japanese Cinema Encyclopedia, treats Kobayashi Satoru’s Flesh Market (1962) as the first true pink film. The classic formula called for a film of about an hour, shot in a week on a very small budget, under a long-standing ban on showing genitals or pubic hair.
The same article covers Nikkatsu’s Roman Porno, where an S&M subgenre began in 1974 when the studio cast Tani Naomi in Flower and Snake, directed by Konuma Masaru and adapted from a novel by Dan Oniroku. Shūkan Gendai notes that Dan’s novel first ran as a serial in Kitan Club from 1962.