The October incident (, Jgatsu Jiken), also known as the Imperial Colors incident (, Kinki Kakumei Jiken), was an abortive coup d'tat attempt in Japan on 21 October 1931, launched by the Sakurakai secret society within the Imperial Japanese Army, aided by civilian ultranationalist groups.

Sakurakai, or Cherry Blossom Society (桜会, Sakurakai) was an ultranationalist secret society established by young officers within the Imperial Japanese Army in September 1930, with the goal of reorganizing the state along totalitarian militaristic lines, via a military coup d'état if necessary. Their avowed goal was a Shōwa Restoration, which they claimed would restore the Emperor Hirohito to his rightful place, free of party politics and evil bureaucrats in a new military dictatorship.The Sakurakai was led by Imperial Japanese Army Lieutenant Colonel Kingoro Hashimoto, then chief of the Russian section of the Imperial Japanese Army General Staff and Captain Isamu Cho with the support of Sadao Araki. The society began with about ten members, active-duty field grade officers of the Army General Staff, and expanded to include regimental-grade and company-grade officers, so that its membership increased to more than 50 by February 1931, and possibly up to several hundred by October 1931. One prominent leader was Kuniaki Koiso, future Prime Minister of Japan. Members of the Sakurakai held meetings in a dojo led by Aikido founder Morihei Ueshiba at the headquarters of the Oomoto religion in Ayabe.

The Sakura group sought political reform: the elimination of party government by a coup d'etat and the establishment of a new cabinet based upon state socialism, in order to stamp out Japan's allegedly corrupt politics, economy, and thought.

Twice in 1931 (the March Incident and the Imperial Colors Incident), the Sakurakai and civilian ultranationalist elements attempted to overthrow the government. With the arrest of its leadership after the Imperial Colors Incident, the Sakurakai was dissolved.

Many of its former members migrated to the Toseiha faction within the Army.