Japan's Invisible Minority: Better Off Than in Past, but Still Outcasts By NICHOLAS D. KRISTOF; New York Times (1857-Current file); Nov 30, 1995; pg. A18, 1 one of Japan's open secrets: ethnic Koreans dominate the organized crime gangs known as the yakuza. More than three-quarters of the members of the Yamaguchi Gumi, Japan's biggest underworld organization, are said to be burakumin or ethnic Koreans.