While rummaging through his grandfather's attic, Hikaru Shindou comes across an old go board. Upon touching it, he hears a mysterious voice and shortly thereafter loses consciousness. When he comes to, he finds that the voice remains and belongs to Fujiwara no Sai, the spirit of an ancient go master. Sai served as a go instructor for the Japanese Emperor during the Heian Era; his devotion to the game transcends time and space, enabling him to continue playing his cherished game as a spectral presence. Sai's primary objective is to perfect a divine go technique that no player has yet achieved, and he aims to realize this by playing the board game through Hikaru. Although Hikaru has no interest in board games, he reluctantly agrees to play, making moves as directed by Sai. However, upon meeting the young go prodigy Akira Touya, a passion for the game gradually awakens within him. Motivated by his new rival, Hikaru's journey into the world of go is only just beginning.