Iwase is a senior concierge working at the Hokkyoku Department Store, a unique retail establishment that caters exclusively to extinct animals. She has brown hair that is cut to neck length and typically wears glasses along with her professional work uniform, which includes a suit and long skirt. Positioned as an experienced and accomplished employee, Iwase serves as a direct foil to the film's protagonist, Akino, a clumsy but well-meaning concierge-in-training. While Akino is prone to making mistakes and over-promising to customers, Iwase embodies the qualities of a seasoned professional, carrying herself with cool confidence and a smooth, graceful demeanor when maneuvering through challenging situations with difficult clientele. Her personality is often described as unflappable, suggesting she rarely loses her composure under pressure. Her distinctive hairstyle, which is styled with a sense of energetic suspension, reflects her dynamic and ever-ready approach to her work, as she frequently appears to swoop in and assist both customers and her junior colleague.

Within the story, Iwase functions as a supportive senior coworker to Akino, standing alongside her fellow senior concierge, Mori, as an example of the high standards the protagonist must strive to meet. Her primary role is to demonstrate the expertise and professional poise required to succeed in their demanding environment. Along with Mori and the strict floor manager Tōdō, Iwase helps to mentor Akino, though she represents the aspirational ideal of a concierge who has fully mastered the art of customer service. Her key relationships are professional, centered on her interactions with her colleagues and the store's animal clientele. There is no information available regarding her background prior to working at the department store, nor is there detail on her personal motivations beyond her evident dedication to her profession. Her development within the narrative is not the focus of the story, as she remains a static character who helps to drive the growth of the protagonist. Her notable abilities lie in her exceptional customer service skills, her ability to handle high-pressure interactions with poise, and her talent for de-escalating potentially difficult situations with a smooth and tactful approach. Her quick thinking and assured manner make her an invaluable member of the concierge team.