Sixth grader Hikaru Shindo stumbles upon a mysterious Go board with a blood stain on it. Before he knows it he's hearing voices, one voice to be exact. The voice of an ancient Go instructor, Sai of the Fujiwara. Sai occupies a space in Hikaru's mind. Hikaru is the only one who can see, hear, or talk to Sai. Sai's one and only desire is to play Go. But he can only do that via Hikaru's body. However, Hikaru has no interest in playing Go. Will Hikaru allow Sai to play? And who is this mysterious young boy, Akira Touya?

Hikaru is now in Haze Middle School and joins the Go club. Akira Toya is now in Kaio. He pays a visit to Haze and challenges Hikaru to a match. Will Hikaru accept to play him?

After Hikaru gets back Yuki's money, Yuki decides to join the club, but refuses to play in the tournament. Tsutsui explains how strong Kaio is and Yuki changes his mind. But will he play without cheating? Meanwhile, Akira discovers that Hikaru is the third board in the tournament and begs the club sensei to put him there. Is Akira willing to give up all his pride and his reputation, just for this one spot?

Hikaru let's Sai play Go online, that way nobody will think Hikaru is really good when in reality he's not.