Keisuke Saito is one of Naoko Watanabe's schoolmates. He sports shaved black hair and small, beady black eyes. His typical outfit includes an olive-colored vest layered atop a light green dress shirt, paired with blue pants and black shoes. Keisuke exhibits an arrogant and rude personality, frequently treating classmates with condescension and acting as though he is superior to them. This behavior persists despite his use of sophisticated language, which contrasts sharply with his overall disrespectful attitude toward peers. His interactions often involve deliberately annoying or provoking Naoko Watanabe, establishing him as a persistent source of irritation within the school environment.