History classes have never interested Saburo. He never saw the point of learning about events from the past, let alone those from a few hundred years ago. But when he falls off a wall, he travels through a wormhole and ends up in 16th-century ancient Japan. He meets a very young Oda Nobunaga, one of the most influential figures in Japanese history, who turns out to be identical in appearance to Saburo. The real Nobunaga, sick of castle life and wanting to travel, orders Saburo to take his place. Without knowing how to get back to his own time, Saburo tries to ensure that history isn't rewritten for the infamous Oda Nobunaga.