Jagaaaaaan

ジャガーン

Shintaro Jagasaki is a beat cop trudging toward a dull, settled life with his girlfriend when a passenger on his commuter train suddenly mutates into a monster. In the chaos Jagasaki's right hand transforms into a living gun shaped like the eggplant mascot of his city, and he kills the creature on instinct. Told that such monsters are "Fractured Humans" warped by frenzied frogs, Jagasaki is drawn into hunting them down across the city, even as the transformation begins reaching people he knows.