One of two timeframes I’d like to see a Yakuza-esque game in, the other being the 50’s post-war Japan.
I was gonna say Ishin is that… but its set in the era immediately prior, the Bakumatsu
Rainbow is a personal favorite, it has a anime, along with a manga that ran well past where the anime ended, tho idk if it got fully legally translated, it was fan translated. Set in and around the 50s.
Barefoot Gen gets bandied about a lot. I never read it personally. Its set on and after Hiroshima’s bombing and the years after. There is a full legal translation of it. Coupla movies too.
No Longer Human by Osamu Dazai was a fantastic bit of postwar literature, though it wasn’t set postwar.