The Amakasu Incident (Amakasu jiken) refers to a crime in which the Lieutenant Amakasu Masahiko was found responsible for the murders of two anarchists and a young boy in September 1923.
Following Japan's Great Kantō earthquake in early September 1923, a police squadron led by Lieutenant Amakasu Masahiko sought out two noted anarchist-socialist leaders, the feminist Noe Itō and her partner, the anarchist Sakae Ōsugi. Together they were beaten and killed by the police along with Ōsugi's six-year-old nephew, and their bodies disposed in a well. Following countrywide outcry, Amakasu was court-martialed and sentenced to 10 years in prison. When Hirohito became Emperor of Japan three years later, Amakasu was released. He studied in France and became a special agent for the Imperial Japanese Army in Manchuria.