One of the participants of the rite, Kaoru is ostensibly invited because of his intellect (graduated top of his university cohort despite his age). Orphaned by a car accident, his aunt Satsuki is his legal guardian and minder during the rite. A schemer who participated in the rite in the hopes of obtaining financial support for his research from the Mikado clan, he is not averse to bugging his competitors when challenging them to board games and blackmailed his aunt to join him after learning her secret so that he could offer her to Heizo as a bargaining chip in return for financial support.