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?

After confronting Hikaru, Akira challenges him to a rematch. As they sit down to play, Sai notices Akira's fangs bearing down on him. Will Sai go easy on Akira, or will he crush him? And, what will happen when the Meijin challenges Hikaru to a game?

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?