The Sanko-gumi was a Japanese yakuza family based in Tokyo which was headed by Shinzuke Onodera during the 1960s. The family competed with Nomoto Enterprises for control of protection rackets, and, in 1963, the two families went to war with each other due to the efforts of the double agent Joji Mizuno. Their war, originating from Nomoto Enterprises reclaiming a racket which the Sanko-gumi had taken from them, and escalating with the Sanko-gumi's retaliatory theft of ¥10 million worth of drug money from Nomoto Enterprises and then with Nomoto Enterprises' murder of Captain Shigeru Takechi, resulted in a final gun battle at Tetsuo Nomoto's mansion, where Onodera, sensing that he would lose the turf war, crashed his explosives-laden car into Nomoto's mansion in a suicide bombing.