Wikipedia
Kantō-kai
The was a Japanese underworld organization formed by Yoshio Kodama in 1964, and named for the Kantō region from which it drew most of its membership. Kodama envisioned the Kantō-kai as a secret national police force, with the aim of forwarding the far right-wing views he and other organized criminals often held.
Kodama had originally envisioned a Japan-wide gangster society, but in 1963 Kazuo Taoka withdrew his powerful Kansai-based Yamaguchi-gumi gang, leaving Kodama with a Kantō-heavy organization.
The group disbanded in January 1965, after only fifteen months, but was a crucial step in uniting the many post-war gangs into a more coherent entity (the modern yakuza) instead of disparate, warring factions.