On December 8, 1963, while partying in a Tokyo nightclub, Rikidōzan was stabbed with a urine-soaked blade by a man named Katsuji Murata who belonged to the ninkyō dantai (Yakuza) Sumiyoshi-ikka. Reportedly, Rikidōzan threw Murata out of the club and continued to party, refusing to seek medical help.[4] Another report states that Rikidōzan did indeed see his physician shortly after the incident, and was told the wound was not serious. He died a week later of peritonitis on December 15. It is rumored by Kimura that his murder was in retaliation for when Rikidozan attacked Kimura during a wrestling match, after Kimura delivered an errant kick to Rikidōzan's groin, ignoring a pre-match arrangement and attacking Kimura for real.[5]