Natsumi Masutomi embodies a complex paradox. To those who don’t know her well, she might seem aloof and distant, her eyes betraying a distrust that can make her appear almost unapproachable. Her androgynous appearance has long been a source of discomfort and misunderstanding, leading her to construct a fortress of emotional barriers. Natsumi holds a stringent code of conduct and operates with a black-and-white perspective on morality, which often casts her as self-righteous. This rigid adherence to rules and structure is her way of establishing a clear identity in a world that frequently leaves her feeling misplaced.

Beneath this seemingly cold exterior, however, lies a deeply caring and compassionate individual. Natsumi’s quiet strength manifests in her role as a protector, particularly toward those she considers part of her inner circle. Though she doesn't openly express her emotions, those who truly get to know her are touched by the depth of her empathy and her genuine concern for others.

The challenges of her androgynous appearance have often exacerbated her discomfort, more because of how others react than from any personal dissatisfaction. The frequent mix-ups about her gender, especially with Milly’s endearing but misplaced assumptions, can be a source of irritation, yet Natsumi finds an underlying humor in these situations, even if she rarely acknowledges it openly. Her defensive reactions, particularly toward men who invade her personal space, are remnants of years spent building walls against unwanted advances. However, within the safety of her group, she is gradually learning to lower these defenses and open up.

In more private moments, Natsumi reveals glimpses of a playful side. She teases those close to her and allows herself rare moments of laughter and light-heartedness, offering a treasured view into her softer side. These fleeting instances are cherished by her friends, showcasing that beneath her disciplined and guarded façade, Natsumi possesses a warm and engaging spirit.