On a trip to Japan in 1595, Dawk Faradayfinds himself befriended by an unpredictable, possibly crazy mountain monk who swears he is being hunted by a demon called a tengu. His sister Hype, meanwhile, bonds with a female samurai who offers her training. These two worlds collide when encounters with demons begin to plague the entire castle town, drawing the Faradays into a multi-century mystery."