Kai Shimada is a professional shogi player of rank 8-dan. When Kiriyama first encountered him, he noticed that Shimada had no notable strengths or weaknesses in shogi.

Shimada's appearance consists of a frail and thin-looking figure alongside his drowsy looking olive green eyes and short brown hair.

He was born in rural Yamagata, and the people in his hometown strongly support him and want him to win the Meijin title.