Dracu-Riot!

"Aqua Eden"—a man-made floating island where gambling, sex trade, and thievery is allowed by the government. But there is one more thing that lurks in the streets of the island-vampires. Mutsura Yuuto is working with one of them, and together with a few other members of their group, they fight to uphold morals on the island.

(Source: jCafe24)