No Guns Life, Vol. 1 by Tasuku Karasuma

[Viz] Ex-soldier Juzo Inui has one question—who turned him into a cyborg and erased his memories? After the war, cyborg soldiers known as the Extended were discharged. Juzo Inui is one of them, a man whose body was transformed, his head replaced with a giant gun. With no memory of his previous life—or who replaced his head and why—Inui now scratches out a living in the dark streets of the city as a Resolver, taking on cases involving the Extended. When a fellow Extended showed up in Inui’s office—on the run from the Security Bureau with a kidnapped child in tow and asking for help—Inui almost throws the guy out. But Inui’s loyalty to a brother Extended makes him take the job. Keeping the child safe won’t be easy, since everyone wants him, from the mob to the megacorporation Berühren, which sends out a special agent who knows exactly how to deal with the Extended…