Kaoru was once a member of Kurei's Uruha, but later, he becomes a member of Recca's team in the Ura But� Satsujin. He wields the K�gan Anki, a puzzle-like weapon that has five different forms. In the manga, the weapon also has a mysterious sixth form: "Mu" (Nothing). At the series end, he follows Kuurei to the past forever leaving his friends.