Two years have passed since Takayuki's mother died of illness... Takayuki hates his father for remarrying without even mourning. Even more than that, he despises his stepmother Ruri, who remarried his father. The beautiful Ruri is friendly and works hard at housework, but this annoys Takayuki even more. One day, Takayuki accidentally witnesses Ruri being raped by a plumber. The sight ignites Takayuki's resentment, and he plots to get rid of Ruri. To start with, he encourages his friend Mitsuru...