Etsusa Oohashi series

越佐大橋

• by Narita Ryohgo
• published by Dengeki Bunko

Set on a giant, almost finished bridge between Sadogashima and Niigata. Abandoned by the government, the bridge, and the giant man-made floating island at the center, has become a city of criminals and societal drop-outs.

• Bow Wow! Two Dog Night

Two gun wielding killers and a gun-hating ex-cop - all with tragic pasts - do some stuff. Rather grim.

• Mew Mew! Crazy Cat's Night

Definitely seems to be conceived as a series that lets him go darker than Baccano, but the dual chainsaw wielding heroine really gave it the spark the first book was missing. This one was a blast.