In the mountains above Japan, Mamoru Yamaemori spends his days tending to his family shrine, fighting Tengu – monsters who feast on human flesh – and making sure his two younger brothers will never have to pick up his mantle. Unable to escape the life forced upon him by his parents and a dark ritual involving Tengu blood, all he knows is that his existence is a curse: he is destined to die young in the service of others. But to fight monsters, Mamoru must dance that line between loving older brother and mindless beast – or else he risks becoming that which he is sworn to destroy.