Hidan no Aria (Aria the Scarlet Ammo) 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 begins airing on April 14th, 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.
Aria H Kanzaki
She is one of the few people that knows Kinji's secret. Her personality is serious and cool. Her first comment about Butei High's skirt is: "Unmarried girls shouldn't openly reveal their legs like this!". However, that notion was pretty much shattered because of Riko's strong influence on her, and she had grown a habit of secretly collecting maid dresses, lolita fashion or any other cute dresses.