Miyuki Iijima is a 16-year-old student with green hair, blue eyes, standing 157 cm tall, and measurements of 81-59-88 cm. She possesses a hot-tempered and aggressive personality, frequently acting on impulse. Her membership in the school's track and field club complements this energetic disposition.

Her primary role focuses on supporting her friend Ai Minamizato's romantic interest in Tooru Nagase. Miyuki actively intervenes to advance their relationship, employing forceful encouragement to push Ai toward confessing her feelings while simultaneously issuing blunt criticism toward Tooru regarding his perceived indecisiveness. This direct approach stems from a protective concern that Tooru might be toying with Ai's emotions.