Aria the Scarlet Ammo (2011)

Kinji Tōyama, a student at a special school for armed detectives called Butei High. He wishes to quit being a Butei, but his plans are disrupted when he meets Aria H. Kanzaki, an elite student, during a bombing incident. They form a partnership, and the series follows them as they work to solve crimes, particularly the case of the "Butei Killer," while navigating their romantic tension and Kinji's secret "Hysteria Mode" ability.