Hamaguchi, Osachi or Yuko (ōˈsächē hämägōˈchē, yōˈkō) [key], 1870–1931, Japanese statesman. He was finance minister (1924–26) and home minister (1926–27) before becoming (1927) president of the Minseito party. As prime minister (1929–30, 1931), he failed in combating economic depression. He pursued a conciliatory policy toward China and compromised with the United States in the London Naval Treaty of 1930 (see naval conferences). These measures were unpopular with the militarists. He was shot by an ultranationalist in 1930 and died in 1931.