Roland Domenig, Vital flesh: the mysterious world of Pink Eiga
Koji Wakamatsu is one of the more important directors to have worked in the pink film (pinku eiga), a genre of softcore, dramatically charged films which were dominant on the Japanese domestic scene in the 1960’s and 1970’s (the roman porn were a more radical and explicit subset of the pink film). The Japanese studios who produced these films, including Nikkatsu, were reluctant to distribute these films abroad, for fear of the sort of image the films would project of Japan. Seeing these films today one must conclude that it was not the more obvious sexual display that worried the Japanese, but the radical anarchist politics of the films, perhaps above all else, often compounded by violent sadomasochism, and the undercurrent of misogyny.
But the star of pink eiga in the 1960s was Koji Wakamatsu. His films combined sex and violence with politics, and hit a nerve with a sexually and politically frustrated (male) youth. In 1965 his film Secrets Behind Walls (Kabe no naka no himegoto) created a scandal in Japan when it was screened at the Berlin Film Festival. The press and the general public regarded the film as a disgrace to Japan and the Japanese film commission unsuccessfully tried to have the film withdrawn from the festival.
David Desser, Eros plus Massacre: An Introduction to the Japanese New Wave Cinema
A contract director for Niikatsu, he [Koji Wakamatsu] directed twenty films in a two-year period, 1963-65. What turned out to be his last film for the company [Secret Act Inside Walls, 1965] found Wakamatsu entering the area pioneered by Imamura Shohei and becoming a growing concern for Oshima, the connections between sexuality, identity, and politics.
Grandfather of the Japanese sex film Koji Wakamatsu pioneered the pinku genre with films like Skeleton in the Closet (Kabe No Naka No Himegoto, 1965) and Violated Angels (Okasareta Hakui, 1967).