Hidan no Aria (緋弾のアリア Hidan no Aria?) is a Japanese light novel series by Chūgaku Akamatsu with illustrations by Kobuichi. As of March 2011, 9 volumes have been published by Media Factory under their MF Bunko J label. A manga adaptation by Yoshino Koyoka started serialization in the seinen manga magazine Monthly Comic Alive on September 26, 2009. An anime adaptation was announced, and began airing on April 15, 2011.
Tokyo Butei High school--- It was a special school where armed detectives, also known as "Butei" are being brought up. Tohyama Kinji is a sophomore student who has the unique body which activates a "super mode" when it was stimulated by "something". He tries to hide it to others in order to live a peaceful life. But trouble came to find him when he became a victim of a bombing incident, where he met the Butei high "Assault" department elite, Aria H. Kanzaki.