Japanese rebel whose attempted coup d'état against the Tokugawa shogunate led to increased efforts by the government to redirect the military ethos of the samurai (warrior) class toward administrative matters.

A famous military teacher in the Japanese capital of Edo (now Tokyo), Yui gained a large following among the local rōnin (masterless warriors). Trained only to fight, these rōnin were without an occupation or means of support. They were thus happy to follow Yui's plan for the overthrow of the new government. The carefully laid plot, originally scheduled to be carried out in June 1651, was delayed, however, when one of Yui's coconspirators became ill. In the interim, the details of the plot became known to the government; many of Yui's followers and family were captured and executed, and he committed suicide.

The revolt greatly shocked the Tokugawa shogunate, which took action to mollify the thousands of rōnin still in existence throughout Japan, providing jobs and retraining them.