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.