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.