Shindou Hikaru, a 6th grader, finds an old go table in the attic of his grandfather's house. He sees some blood stains on the go table, and tries to wipe it off... when a ghost dressed in Heian period clothes pops out, and takes over his body.
The ghost happens to be Fujiwara no Sai, a member of the court during the Heian period. Sai was one of the two men who was assigned as the go tutor to the emperor. The other tutor was envious of Sai, and challenged him to a go match -- whoever wins gets to stay as the court's go master. Sai's opponent cheats during the match, and before Sai could say anything about it, the opponent accused Sai of cheating. Sai was banished from the court, and because of regret and anger, he committed suicide. But as with all unrepented souls, Sai was unable to leave the material world... until he is able to master go, and get one step closer to "kami no itte," or god's hand.