Otoya Yamaguchi (山口 二矢 , "Yamaguchi Otoya" , February 22, 1943 – November 2, 1960) was a Japanese ultranationalist who assassinated Inejiro Asanuma, a politician and head of the Japan Socialist Party. Yamaguchi was a member of a right-wing Uyoku dantai group, and assassinated Asanuma by yoroidōshi on October 12, 1960, at Tokyo's Hibiya Hall during a political debate in advance of parliamentary elections.