Ōshio Heihachirō (大塩 平八郎, March 4, 1793 – May 1, 1837) was a Japanese philosopher, revolutionary, writer, and yoriki who led the Wang Yangming school (陽明学, youmeigaku) in Osaka.

At the age of 15 he discovered while researching his family's personal archive that one of his ancestors had been labeled as "dishonorable" because he spent much of his time writing in the company of prisoners, criminals, and commoners in defiance of social taboos.

At the age of 24 he read a book about the morals and precepts of Chinese philosopher Lü Kun (1536–1618) and later studied the works of his master Wang Yangming.

Agriculture and food production experienced a crisis due to a combination of failed harvests in both 1833 and 1836, the high taxes imposed by the national government, and the self-interested actions of local officials who were insulated from accountability by Japan's centuries-old caste system.

The population protested against the sharp increase in food prices and began engaging in uchikowashi (destroying the residences of those deemed to be complicit in inflation) as an act of resistance.

Ōshio's first instinct was to appeal directly to his fellow high-caste samurai and the wealthy residents of Ōsaka, in particular the merchants who controlled the supply of food.

The rich cared little for the welfare of those they saw as beneath them, and in any case, there was much more to gain from exploiting the crisis: profiteering, usury, and the buying up of land and properties from impoverished residents soon became commonplace.

The insurgents were poorly trained, equipped, and led, and while the shogunate could only send a hastily raised militia to deal with them, the government troops had superior weapons, armor, and leadership.

[5] Yet despite its failure, Ōshio's rebellion, and the mere fact that one of the bakufu's own officials was behind it, helped spur important debates about the necessity of Japan opening itself up to the world.