Among “those flattened people” was Chojiro Watanabe, a yakuza leader with a solid grip on Hiroshima’s criminal underbelly. According to Andrew Rankin’s YAKUZA: A 400-YEAR HISTORY OF THE JAPANESE UNDERWORLD (Basic Books, $32), Watanabe’s death cast the already benighted city further into lawlessness, with his successors vying for control of its supply chains, street markets, and gambling houses—crisis exploitation at its finest. Armed robberies and shoot-outs became commonplace. Japanese servicemen, unemployed and widely disparaged, joined gangs to make some quick cash. No longer in the mood for taking orders, they gave free rein to their most violent impulses, sometimes with the help of methamphetamine. In the ensuing turf wars, one leader lost his entire arm to a sword. …