Kekkai Sensen – Mafuugai Kessha

From Dark Horse:
Three years ago, a gateway between Earth and the Beyond opened over the city of New York. In one terrible night, New York was destroyed and rebuilt, trapping New Yorkers and extra-dimensional creatures alike in an unassailable island, a world all its own hidden in the mist of its physics-defying waterfalls.
New York has been rechristened Jerusalem’s Lot, a paranormal melting pot where magic and madness dwell alongside the mundane, where every form of human vermin gathers to exploit otherworldly assets for earthly profit. Now someone is threatening to breach the controlled flow of unharmful, average humans and items in and (much more rarely) out of the city and thereby release Jerusalem’s Lot’s deluge of horrors on The Outside. The mysterious super-agents of Libra fight the impossible to prevent the unthinkable.
Each volume has a subtitle:
Vol. 1 魔界街結社 (Mafuugai Kessha) Secret Society in the Sealed City of Magic
Vol. 2 世界と世界のゲーム (Sekai to Sekai no Game) A Game Between Worlds
Vol. 3 震撃の血槌 (Shingeki no Blood Hammer) The Tremorous Blood Hammer
Vol. 4 拳客のエデン (Kenkaku no Eden) A No-Holds-Barred E-den
Vol. 5 Ｚの一番長い日 (Z no Ichiban Nagai Hi) Z’s Longest Day
Vol. 6 人狼大作戦 (Jinrou Daisakusen) Chain: Possible
Vol. 7 マクロの決死圏 (Macro no Kesshiken) Desperate Night in the Macro Zone
Vol. 8 幻界病棟ライゼズ (Maboroshi Byoutou Rises) The Phantom Hospital Rises
Vol. 9 鰓呼吸ブルース (Erakokyuu Blues) Branchial Respiration Blues
Vol. 10 妖眼幻視行 (Yougan Genshikou)
Japanese manga and anime site: http://kekkaisensen.com/