Isumi Kominato lives with her parents and her fisherman grandfather. Her personality is determined, outgoing, and kind, though she withdraws from others when upset, avoiding any show of weakness. She speaks up against perceived wrongs and proves capable when focused.

Athletically inclined, she enjoys running. However, a decisive defeat by a classmate in a race caused a significant loss of confidence, profoundly impacting her self-belief. Her running speed reaches 10 meters per second (36 kilometers per hour).

Physically, she has light brown hair typically in a high ponytail secured with a pink scrunchy. Her standard attire is a blue coat over a pink chequered dress, paired with a long pink scarf extending to her waist. Alternative outfits include goggles on her head, high-heeled shoes, an ankle-length scarf, and a flower pin attached to the scarf. The scarf remains a consistent element in her appearance.

Her development focuses on rebuilding self-confidence through shared challenges and teamwork. Initially withdrawing after setbacks, she gradually learns to rely on others, discovering inner strength through collective effort. This journey involves confronting her fears and insecurities directly.