Iruru Yorozu is a seventeen-year-old third-year high school student and a core member of the theater company Eden. She has long brown hair, often tied into a side-tail with a black ribbon, and avocado green eyes with her bangs parted to cover part of her left side. A notable mole, known in Japanese folklore as a nakibukuro, sits under her left eye. Her physical presence is marked by a sense of grounded maturity, often described as having an old man-like or worldly-wise nature that contrasts with her youthful appearance.

Iruru is a veteran of Eden and has a long-standing history with the company and its leader, Hatsumi Renjakuno. Her background is defined by a past aspiration to reach the pinnacle of theatrical stardom, a dream that gradually faded as she confronted the limits of her own talent. Despite dedicated effort, her acting stagnated, and she became resigned to playing supporting roles, having given up on the idea of becoming a World Dai Star.

Her personality is a blend of cheerful helpfulness and deep-seated frustration. On the surface, Iruru is extremely accommodating and acts as a reliable mediator within the often-troubled Eden, known for her ability to directly tell others to calm down. However, this outward stability masks a growing resentment at being constantly relied upon and a profound insecurity regarding her abilities as an actress. She carries the burden of being "normal" in a troupe of highly eccentric and talented individuals.

This internal conflict stems directly from her unique theatrical gift known as a Sense, named Average Hitter. This Sense allows her to perform any role competently, achieving a passing score with every attempt. The crucial and painful limitation is that it makes it impossible for her to ever achieve a perfect score or elevate her performance beyond that baseline of adequacy. While she herself is deeply insecure about this inability to perform perfectly, her ability is highly valued by Hatsumi, who sees it as an essential tool for creating a solid and reliable foundation for any theatrical production. In her free time, Iruru enjoys watching sports like baseball, horse racing, and keirin, as well as playing mahjong, demonstrating a fondness for gambling and probability-based hobbies.

Within the story, Iruru serves as a stabilizing anchor for Eden, providing a grounded counterpoint to the more volatile members. Her key relationships are shaped by her role as the dependable, long-standing member. She is a childhood friend of Kamira Akiru. She is heavily relied upon by Hatsumi, who values her practical sense of stagecraft. She acts as a supportive, if somewhat worried, senior to the younger and more innocent Nikako Toneri, whom she sees as a form of personal stress relief from the pressures of dealing with the rest of the troupe. Her dynamic with other members involves mutual observation and gentle friction, such as advising the competitive Shigure Fudeshima or appreciating the advice of the perceptive Daikoku Karasumori.

Iruru’s personal development revolves around navigating her resignation and frustration. She has contemplated that a sincere, all-out attempt to break past her limits, should it end in failure, might completely break her spirit. As such, her journey is one of accepting her role as a master of the passing score while coping with the bitter knowledge that true excellence remains forever out of reach. Her loyalty and helpful nature keep her engaged as the cornerstone of her theater company, even as she struggles with the quiet disappointment of her unfulfilled ambition.