Koji Seki (???, Seki Koji) aka Takashi Seki (??? or ???, 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.