Mio Fuyutsuki is a young adult woman of average height with wavy brown hair reaching her upper back and matching brown eyes. Her office attire typically features blouses, skirts or brown pants, pantyhose, and high heels. Casually, she wears stylish yet practical clothing like swimsuits, jackets, scarves, dresses, t-shirts, and shorts. For sleep, she prefers a long grey shirt with grey trousers. Her facial expressions are usually neutral, though she sometimes smiles or shows moments of bashfulness. Peers perceived her as stoic and cold during high school, negatively impacting her self-worth and leading her to believe she was boring. This perception carried into her professional life, where colleagues initially misinterpreted her reserved demeanor. However, her kind actions and genuine care gradually revealed her warm-hearted nature, earning acceptance and friendship. Professionally, she proves reliable with strong problem-solving skills, often resolving difficult workplace issues. Her calm, focused work ethic garners respect. Despite her quiet exterior, she shows perceptiveness, particularly understanding others' limitations, like a colleague's inability to interact with plants or pets due to supernatural ice abilities. She offers practical solutions, such as gifting straw packaging to protect plants or sharing her cat's whiskers as safe mementos. She owns a cat named Nyamero. Her relationships evolve significantly. She develops a close friendship with Komori, spending time together outside work with other colleagues. Himuro's younger sister, Yukimin, admires her after meeting on a ski trip and occasionally visits her apartment. Romantic developments center on her relationship with colleague Himuro. Initial interest sparks encountering him frozen due to nervousness on his first day. Working in the same department brings them closer, though she remains unaware of her own romantic feelings initially. Interactions increase her emotional expressiveness, like visible surprise during an aquarium visit. When a succubus friend attempts to charm Himuro by kissing his hand, she publicly claims him as hers. By the narrative's later stages, they enter a confirmed relationship, agreeing to use first names privately. Key moments illustrate her development. On an Okinawa business trip, she assists Himuro in managing his ice powers by creating a surf drum for practice and cares for him during a heatwave-induced physical shrinkage, admitting she finds his child form endearing. On an overnight work trip, she tends to Himuro when fever reverts him to a childlike state, including a moment where he semi-consciously leans over her in bed before she sleeps on the sofa to maintain boundaries. She privately keeps a phone photo of his child form. A year after their first meeting, they revisit their initial cherry blossom viewing spot, reflecting on their journey. Her behavioral patterns include a strong sense of duty and conformity to expectations, seeking security through established structures and authority figures. She balances professional seriousness with underlying compassion, increasingly expressing warmth and protectiveness within close relationships while maintaining personal boundaries.