Sayako Kuwahara is a second year high school student who is described as being random and spontaneous, often changing her interests and goals. During her first year, she joins the Kendo Club, but would sometimes disappear for short periods of time, claiming to quit. She and Kirino have known each other since elementary school, and Kirino often calls her "Saya." She is one of the tallest members on the team, which others poke fun at by "mistakenly" calling her a boy. In the storyline, she was seen to improve her footwork tremendously after a brief teaching session from Tamaki. Sayako, like Kirino, thinks that Tamaki is cute, as she and Kirino will sometimes do silly things to Tamaki (i.e., playing with Tamaki's hair, not listening to her kendo lectures, making Tamaki fight merely because she wants to see her fight, etc.). She is rather pessimistic, and always claims to pursue death the moment she fails at something. In the anime, her writer's hobby is seen when telling stories, like explaining why Asuma quit kendo in a dramatic fashion (although her friends gave her three points since they found her "story" uninteresting).

She plays the position of Center (Chuken) in the competition.