Hikaru no Go.

Hikaru Shindo is like any sixth-grader in Japan: a pretty normal kid with a two-tone head of hair and a penchant for antics. His life completely changes when he finds an old bloodstained go board in his grandfather's attic. The ghost of an ancient go master named Fujiwara-no-Sai was trapped in the board and soon becomes a part of Hikaru's consciousness. Together Hikaru and Sai make an unstoppable go-playing team!