Kōji Seki (関孝二, Seki Kōji) aka Takashi Seki (関孝司 or 関孝志, Seki Takashi) (born September 20, 1911, date of death unknown) was a Japanese film director, known for his pioneering work in the pink film genre. Among the accomplishments of Seki's career: he directed the first pink films for Kokuei, the oldest pink film company, Japan's first 3-D film, the world's first 3-D sex film, and Japan's first "invisible man" pink film. ()