Kōsuke Kiyotaki is a 9-dan shogi player and a supporting character in The Ryuo's Work Is Never Done!. He serves as the master of both Yaichi Kuzuryū and Ginko Sora, and is the father of Keika Kiyotaki. His wife passed away from illness many years ago, and this loss has made him especially devoted to his only daughter, whom he treasures deeply. He regards his disciples, Yaichi and Ginko, almost as if they were his own grandchildren, and he takes an active, caring role in their lives and development.

Kiyotaki has a calm and patient demeanor, and he typically maintains a composed exterior. He is deeply knowledgeable about shogi, having reached the high rank of 9-dan, and he uses his experience to guide his disciples through both the technical and psychological challenges of professional play. His motivation centers on nurturing the talents of those he mentors and protecting his family, especially Keika. He is a steady, reliable figure who provides wisdom and support without seeking personal glory.

In the story, Kiyotaki acts as a mentor to the protagonist Yaichi, offering counsel during critical matches and helping him navigate the pressures of holding the Ryūō title. He also trains Ginko Sora and watches over the younger shogi players who enter his circle. His relationship with Yaichi is built on mutual respect and trust, while his bond with Keika is close and protective. Over the course of the series, Kiyotaki remains a constant, grounding presence, his own growth primarily reflected in his willingness to adapt his teaching methods to the unique talents of his students. His notable ability is his mastery of shogi at the highest professional level, which he uses to analyze games and provide strategic insights that shape the careers of those around him.