Oniroku Dan's Snake Hole (団鬼六・蛇の穴 Dan Oniroku: Hebi no ana) is a Roman Porno film directed by Katsuhiko Fujii and starring Izumi Shima. Historians of the genre consider this film to be the beginning of the end of Nikkatsu's Roman Porno series. Nikkatsu had publicly disparaged the new AV (Adult Video) competition as inferior to the studio's own theatrical product. Yet, according to the Weissers, this film mimics the contemporary AVs, with which it differs only by being shot on film rather than video tape.