Saki Matsuga is a high school student and lifelong childhood friend of Moe Uzumasa, living near Matsugasaki Station. Her athleticism shines through track and field club membership, with running as a standout skill. This physical prowess fuels her competitive and energetic nature, occasionally revealing impatience that contrasts with her friends.

Her closest bonds center on enduring friendships with Moe and Misa Ono, their interactions radiating deep-rooted camaraderie. As a Kyoto native, she naturally speaks in the local dialect. Visually, she consistently displays dark skin in her character depictions.