Director Hirotsugu Kawasaki adapts author Takafumi Takada's popular fantasy novel into a sweeping anime adventure in which a young boy who travels back in time to lead mankind in a war against invading demons. Jun Tendo is a timid 15 year old who suddenly finds himself thrust 1,200 years into the past, when the human race faces certain extinction at the hands of powerful demons. Just when it looks like all hope is lost, Jun unleashes his inner hero and discovers powers he never thought possible. As the battle begins, the once-shy teen discovers the inner-courage to save the world, and drive the demons back into darkness.
by Jason Buchanan synopsis