Yoshinari Bessho, the feudal lord of Tanba Province, is a collector of butterflies and has his concubines tattooed with butterflies as well. One day while hunting, Yoshinari sees Gennosuke Akizuki's beautiful wife, Okoto. He kidnaps her, tattoos a butterfly on her shoulder and takes her for his own. Feeling shame for what has happened, Okoto throws herself into a well and commits suicide. She then returns as a ruthless ghost that seeks revenge against Yoshinari and his retainers. Whenever the ghost appears, mysterious butterflies always fly around her...

A highly contagious incest virus induces several generations of a Japanese family to have sex in all possible constellations and across gender boundaries – and with that man in a bear costume who suddenly appears? Only in Japan!