New Underground History of Japanese Violence: Vengeance Demon 1969

A brother and sister live as outcasts from their hamlet due to a belief that mental illness runs in their family. A group of villagers plot to steal their property by beating and hanging the brother and gang-raping the sister. Believing the brother to be dead, scheming to kill the sister, and making both deaths look like accidents... unbeknownst to them, the brother survives and proceeds on a mission to slaughter those responsible in the hamlet.