In May 1938, 21-year-old Toi Mutsuo was severely depressed and suffered from tuberculosis, which at the time was an incurable and terminal illness. He lived in the small village of Kaio, on the outskirts of Okayama in Japan. Mutsuo’s parents died when he was very young, forcing him to be brought up by his grandmother. His depression began when local women started to reject his advances because of his suffering of tuberculosis. Before the massacre, Mutsuo wrote suicide notes that implied the reason for his actions was the pain of rejection by his peers.
In the early hours of May 21st, 1938, Mutsuo used an axe to kill his grandmother via decapitation. He then proceeded to cut the electricity line to the village and strapped two torches to his head, before systematically moving from house to house and killing anyone he found inside. He used a shotgun for most of the killings, though he also made use of the axe and a katana. Before the sun came up, he committed suicide by shooting himself in the chest with the shotgun, but not before he’d taken the lives of 30 innocent people. At this point in history, the massacre perpetrated by Mutsuo was the worst ever to be committed by an individual.