After the attempted assassination of Prime Minister Osachi Hamaguchi, Prince Kinmochi Saionji (the last genrō ) and Lord Privy Seal Makino Nobuaki considered recommending General Kazushige Ugaki to the post of prime minister. However, they later decided that a civilian nominee would be best for Japan at the time. This change incensed the militarist party within the Imperial Japanese Army, and several leading generals called on Hashimoto and his Sakurakai to plan a coup d'etat to bring Ugaki into power.
Hashimoto's plan involved a three-phase program :
1. Massive riots would be instigated in Tokyo, which would force the government to call-out troops and proclaim martial law.
2. The Imperial Japanese Army would execute a coup d'etat and seize power.
3. A new Cabinet would be formed under the premiership of the then-War Minister, General Kazushige Ugaki.
The project was underwritten by a 200,000 Yen donation by Yoshichika Tokugawa, ultrarightist member of the House of Peers, son of the last daimyo of Nagoya, founder of the Tokugawa Art Museum, Nagoya and Emperor Showa's second cousin.
Ultrarightist civilian organizations led by Kanichiro Kamei and Shūmei Ōkawa, fomented a commotion outside the Diet Building in Tokyo late in February 1931. However, due to logistics difficulties, the disturbance failed to attract enough people, and the hoped-for riot failed to occur. Hashimoto consulted with Ōkawa, who wrote Ugaki on 3 March 1931, explaining the plot and demanding the call-out of troops and action on the general's part. Ugaki, either lukewarm from the start, or having a change in heart after seeing the failure of the riot to take off in February, refused to cooperate. Ugaki had hopes of becoming head of the Rikken Minseito party, and thus had a chance of becoming prime minister by legal means, rather than a coup. It is also likely that Ugaki foresaw that a military dictatorship would alienate powerful sectors of the Japanese elite (bureaucrats, court nobles, zaibatsu industrialists, etc) whose support he would need in case of a total war.
The plotters attempted again to start a riot again on 17 March 1931 (two days before the planned coup d'état was to take place), but again the projected 10,000 rioters failed to materialize, and the leaders were this time arrested and the whole affair disintegrated.