From Mangahelpers:
One day, a young man named Himuro Shousuke shows up out of nowhere, claiming he wants to become a shogi master. When he is told that he must follow the appropriate channels to become a pro shogi player, he produces a recommendation from a highly respected master, Mikami Sankichi. Shousuke claims he trained with Sankichi in Kochi, and now he's ready to skip the early steps of becoming one of the elite. People are understandably skeptical, but Shousuke begins to beat the skilled players they match him up with. Some are unhappy about an outsider coming into their hierarchy at a high level, but will they be able to stop his rise? The future is full of the internal politics of the shogi world and exciting shogi matches.

Note: Gekka no Kishi won the Shogakukan Manga Award in 1997.