Based on

TV Shows like Evil Dragon War Chronicles (1987)

Back in the era of Empress Himiko, Japan was ruled from the shadows by a secret chaste of shamans called Kidō (鬼道). Although they were exterminated by fear of their power, some of them survived through the centuries, hoping to recover their power by summoning the Four Holy Beasts in human bodies. Their last attempt, performed by esotericists in the Mount Koya, was stopped in 1971 by one of their own creations, a monk with the power of Genbu named Gendo.