The Shinkai-gumi was a Japanese yakuza family and a subsidiary of the Yamamori-gumi of Hiroshima Prefecture. It was founded by Uichi Shinkai, an underboss of Yoshio Yamamori, and engaged in methamphetamine trafficking during the early 1950s. In 1954, Shinkai decided to go to war with a rival underboss, Tetsuya Sakai, after Sakai and Toru Ueda made moves to gradually seize control of the family from Yamamori, and he allied with Yamamori to wipe out the Sakai faction (which made enemies with both of them due to his opposition to both methamphetamine trafficking and to Yamamori's 70% cut of his lieutenants' profits). The Shinkai faction succeeded in killing Ueda at a barbershop, but, in the ensuing gang war, the Shinkai-gumi and the remnants of the Doi-gumi were both wiped out by the Sakai faction in the ensuing gang war. Ultimately, Shinkai was stabbed dead and his lieutenant Toshio Arita was arrested by police for attempting to plow through a police roadblock, and his subsidiary family dissolved.