Kai Shimada is a professional shogi player of rank 8-dan.

Spoiler

When Kiriyama first encountered him, he noticed that Shimada had no notable strengths or weaknesses in shogi.

Shimada possesses a calm and collected personality. At first, it seems like he's very plain, but as seen on his game with Rei he has a very intimidating yet serene personality. He's observed to be caring over fellows under him like Nikaidou. Shimada is very kind to his fellow shogi players and tries to help them improve their game.

Spoiler

He runs a study group consisting of himself, Kiriyama, Nikaidou, and Shigeta.