In this narrower sense, Nikkatsu cinema Roman Porno series, Toei's Pinky Violence series and the Tokatsu films distributed by Shochiku would not be included as these studios have much larger distribution networks.
Until the early s, they were almost exclusively shot on 35mm film. Recently, filmmakers have increasingly used video while retaining their emphasis on soft-core narrative. Many theaters swapped japanese for sex projectors and began relying on old videos to meet the demand of triple-feature showings.
This article places the pink film in the larger context of postwar erotic cinema. Pink films became wildly popular in the mids and dominated the Japanese domestic cinema through the mids.
Japanese Cinema Encyclopedia: The Sex Films
Aroundthe major studio Nikkatsu started focusing almost exclusively on erotic content, but Toeianother major film production company, started producing a line of what the to be known as Pinky Violence films. With their access to higher production values and talent, some of these films japanesse movie sex critical and popular successes.
The "pink film," or "eroduction" erotic production as it was first called,  is a cinematic genre without an exact equivalent in the West. The Japanese film ethics board Eirin has long enforced a ban on the display of genitals and pubic hair.
This restriction forced Japanese filmmakers to develop sometimes elaborate means of avoiding showing the "working parts", as author Donald Richie puts it.