The Sengoku Family (千石組, Sengoku-gumi) are a subsidiary of the Omi Alliance.
According to the Omi Fifth Chairman, Jin Goda, in 2006 the Sengoku Family are "new blood" within the organization, meaning they were formed relatively recently. Despite this, the Sengoku Family is the single most wealthy family within the Alliance.
The Family's Patriarch and founder, Toranosuke Sengoku, makes it a habit to display his family's affluence: Operating out of a golden castle in the outskirts of Osaka, where his bodyguards are dressed like ninja and samurai; buying his soldiers and officers expensive suits to wear while on the job; keeping a pair of tigers as pets and generally throwing money around to demonstrate his power.
Yakuza 2 Edit
During the Tojo-Omi War of 2006, the Sengoku Family makes a secret pact with the Nishikiyama Family of the Tojo Clan: The Nishikiyama will stage a coup in the Tojo HQ and take over while Sengoku and his forces march on Tokyo to usurp the Tojo's control over the city. In exchange, Nishikiyama Patriarch Koji Shindo would be allowed to serve as the Sixth Tojo Chairman under Sengoku's protection. Ultimately, the plan was thwarted when Kazuma Kiryu and Daigo Dojima stopped Shindo's coup and Goro Majima's gang, the Majima Construction Company, repelled Sengoku's forces in Kamurocho.
Sengoku later tried to assassinate Kiryu by luring him into a trap at his castle, under threat of executing his captive, Kiryu's adoptive daughter, Haruka Sawamura. This plot also failed, as Kiryu was able to defeat all the minions Sengoku threw at him, including the Family Captain, Kunieda, and his two pet tigers. As a result, Ryuji Goda, furious at Sengoku's underhanded attempt at killing Kiryu before he could, proceeded to kill Sengoku by stabbing with his katana and throwing him out of his castle's top floor.
It is unknown what became of the Sengoku Family after 2006, as they are not mentioned within the franchise again. By 2012, the Family is no longer amongst the Omi Alliance's most prominent organizations, so they could have been disbanded or simply ceased to be as powerful as they once were.