Taoka returned to the gang after leaving prison in 1943. In October 1946, Yamaguchi died, and Taoka, then thirty-three, stepped in to lead the gang. Despite the decline of the gang both in size and power as a result of the war, Taoka used his ferocity and his tremendous ability to organize the remaining members. He returned to the Kobe docks and founded the Yamaguchi-gumi Construction Company. Simultaneously he took a larger share of the local gambling and extortion rackets. Starting in the 1940s, Taoka's gang began a systematic expansion into the lucrative territory of other gangs. The local Honda-kai were absorbed, as were the Meiyu-kai and their territory in Osaka, and the Miyamoto-gumi.
In addition to absorbing other gangs and their territories and shares of the rackets, Taoka expanded into the entertainment field, with a talent agency that pushed Osaka-area performers and a touring group called the Home Run Hit Parade. Despite his expansion, the heart of his business remained in the Kobe docks, where, by the mid-1960s, the Yamaguchi syndicate controlled almost 80 percent of all cargo loading.
At the zenith of Taoka's thirty-five-year career as the godfather of Japanese syndicates, he controlled hundreds of gangs and some 13,000 yakuza. Attracted by the power of his organization, right-wing politicians, including the powerful Kodama Yoshio, backed his operations. In return, Taoka, like other yakuza bosses, lent his troops in support of the anti-Communist agenda of the right-wing faction. Through Kodama, Taoka was introduced to, and eventually became a blood brother with, Machii Hisayuki, Korean boss of Tokyo's Tosei-kai. Through this new alliance, the Yamaguchi-gumi expanded into Tokyo as well. By the time Taoka died of a heart attack in 1981, his organization was grossing over $460 million annually. Taoka's greatest contribution as a yakuza boss was in opening doors into Japan's rapidly expanding economy for the Japanese underworld. In addition to the standard underworld pursuits of gambling, prostitution, and extortion, Taoka was single-handedly responsible for introducing the mob into professional sports and entertainment, including the lucrative film industry. See: Inagawa Kakuji; Jirocho Shimizu no; Kodama Yoshio; Machii Hisayuki; Nakasone Yasuhiro; Ogawa Kaoru; Osano Kenji; Sasakawa Ryoichi; Toyama Mitsuru; Yakuza