Hikaru No Go 18: Six Characters, Six Stories

Hikaru Shindo, a pretty normal Japanese sixth-grader, finds an old, bloodstained Go board in his grandfather's attic, and soon he discovers that Fujiwara-no-Sai, the ghost of an ancient Go master, is trapped inside the board, but when Sai becomes a part of Hikaru's consciousness, together they make an unstoppable Go-playing team.