Reiko Toono teaches at Jōran High School and serves as Haruo Yaguchi's homeroom teacher. She possesses black hair and aubergine-colored eyes, maintaining a professional appearance. Initially strict, especially towards Yaguchi, she exhibits a commitment to student development. When Yaguchi focuses on academic improvement, she shifts from harshness to a more encouraging role and supports his efforts. Her character consistently fulfills a professional, supportive teacher role across all official media.