Kai Shimada

Class A, 8th dan. In his mid-30s when first introduced, the same age as Fuyuji Soya and a fellow student in the encouragement association. However, due to his slim build and thinning hair, he is often mistaken for someone in his 40s, like Goto. He mentions using a "special" shampoo as a countermeasure against hair loss.

A static rook player. A man of character and the senior disciple of Nikaido, he shares a close relationship with Nikaido, referring to each other as "Bou" and "Anija." He is considerate of his juniors and acts like an older brother to Nikaido. Rei faces him in the Lion King Tournament challenger decision match and wins. Afterward, he invites Rei to his study group, gradually deepening their interaction. Normally a calm person, he shows a combative side during matches. As the leader of the study group, he showed a complex expression when, during Rei's final year of high school at the Lion King Tournament, all members of the study group advanced, making it inevitable for him to face one of them. He also pondered the significance of continuing the study group.

Originally from a depopulated mountain village near Tendo City, Yamagata Prefecture, he helped with fruit harvesting and dairy farming to earn money for transportation to the encouragement association, becoming a professional shogi player through hardship. He is a compassionate person who has created a shogi club to prevent the elderly in his increasingly depopulated hometown from becoming isolated, respected by a journalist who has covered him for many years and by Rei. Recognized by himself and others as a "person of effort," he is highly motivated and does not shy away from effort to improve his shogi skills, pouring as much energy as possible into shogi, often at the expense of his relationships with women. He had a girlfriend in his hometown, but they parted ways because he prioritized shogi. Even after she had a child with another man, he continues to remember her as "the cost of the path chosen in shogi."

He has had stomach pains since his time in the encouragement association, often joked about in the story. Known by himself and others as a "rain man," as a child, he was frequently taken to mountain shrines to pray for rain (his family informed the school, so it was not an unauthorized absence), and about 70% of the events he attended brought rain. While he shows discomfort when Rei tries to connect him with Akari, he shows relief when he sees Rei smiling next to Hinata.

According to the original author, Shimada's model is Kuranosuke Sasaki, and he was very pleased that Sasaki played Shimada in the movie version.

In episode 19 of the anime, his grandfather (voice - Tomisaburo Horikoshi) appears.