The protagonist of the story, Riku is a high-school student whose lives with his father and stepmother, Shizuru. He was in love with Shizuru's younger sister, Amane, but she is presumed dead two years ago in a fire. After sustaining, at the start of the series, a fatal wound from a Kanshu, Neene turns Riku into a special Kanshu that can retain his own consciousness as long as he has a Jinki. His Jinki is given by Youhei and takes the form of a chainsaw-like sword with trigger grip.