Project ARMS Vol 8

From the VIZ Media edition

Ryo, Hayato, Takeshi and Kei are Arms - kids implanted with nanotech limb enhancements that cause them to transform into grotesquely deformed and out of control superweapons. Their desperate quest to uncover the secrets of their pasts takes them to a tiny desert town in Arizona called Gallows Bell. The horrifying reality that awaits them there could be more shocking than they can handle!

Source: Anime News Network Encyclopedia