Against such background, on December 27, 1923, an attempted assassination occurred where Prince Hirohito (who later became Emperor Showa) was sniped by a young man, Daisuke NANBA, a self-proclaimed communist, when the Prince was on his way to open the new Imperial Diet session, but fortunately he was unhurt (the Toranomon Incident).
このような中での大正12年（1923年）12月27日、帝国議会の開院式に望んだ摂政裕仁親王（後の昭和天皇）が、自称共産主義者の難波大助という青年によって狙撃されるという事件が起こったが、幸いにして裕仁親王は無傷であった（虎ノ門事件）。