Masayoshi Satsuki is a Life Guidance teacher at Kuzuryū High School who serves as the club advisor for the boys' basketball team. He was appointed to this position at the request of the school's principal. Satsuki lives in Kanagawa Prefecture, and his wife is expecting their first child. The team members refer to him as Satsuki-sensei.

As an advisor, Satsuki provides supervision and guidance to the basketball club rather than coaching them in a technical capacity. His role is primarily administrative and pastoral, ensuring the team operates within school regulations and supporting the players' personal development. He is a responsible and principled figure who upholds discipline and structure, reflecting his background as a teacher. While he does not possess notable basketball abilities himself, his steady presence allows the team to focus on growth and competition.

Satsuki maintains a supportive relationship with the team members, particularly Momoharu Hanazono, whom he seems especially close to among the students. Throughout the story, he acts as a stabilizing influence, encouraging the players to pursue their goals while keeping their behavior in check. His own personal life, including the impending arrival of his child, occasionally adds a layer of warmth and realism to his interactions.