Reo Igarashi, the 22-year-old leader and center of underground idol group ChamJam, sports dark pink hair and matching eyes. Her signature outfit is a hot pink and white dress paired with long white socks and bootstrapped boots. Born October 25th with blood type AB, she collects teddy bears.

Her past in the idol group Melty, where she was the least popular member and endured belittlement from the center, Mei, fuels her supportive leadership in ChamJam. Reo leverages her industry experience to mentor members, advising Maina Ichii on professional boundaries with fans while encouraging her to request fan letters during performances. She frequently reassures Maina of her value and comforts her during self-doubt. Reo steps in as a substitute during events like sports festivals when members tire. Her humility shines through with fans, especially her deep appreciation for supporter Kumasa.

Despite her confidence, unresolved feelings towards Mei linger. Reo feels overlooked when Mei ignores her during a TV appearance and views Mei's new group, Maple Doll, as a rival. Learning Maple Doll will perform at Budokan prompts Reo to confront Mei at the Setouchi Idol Festival. She counters by asserting ChamJam prioritizes enjoyment over prestigious venues, demonstrating her growth in valuing intrinsic motivation.

Within ChamJam, Reo shares a close bond with Sorane Matsuyama, catching the first snowfall together. She demonstrates care for Maina by taking her shopping for Santa costumes before a Christmas event. Reo further connects with fans by participating in a New Year's midnight countdown show. Her surname, Igarashi (combining the characters for "fifty" and "storm"), reflects her journey as a resilient yet compassionate leader who channels past struggles into supporting her group.