Yurume Aida, an 18-year-old recent high school graduate, moves from her rural hometown to Tokyo aiming for admission to Tokyo University. She becomes a "ronin," dedicating an extra year to preparing for the demanding entrance exams. Her relocation lands her in Maison du Wish, a low-cost, dilapidated apartment building on Tokyo's outskirts, a stark contrast to her expectations of city life. This boarding house serves as home to fellow ronin students facing similar academic pressures and financial constraints.

Though academically ambitious, Yurume's days frequently drift from structured study. She engages deeply in communal life with neighbors Sae Kawano, Kumi Tanaka, and Matsukichi. Their interactions revolve around adapting to tight budgets, shared living inconveniences, and inventing cheap pastimes. Recurring activities include weathering seasonal extremes together—finding relief from summer heat and warmth in winter—plus group meals like hot pots using pooled ingredients. Financial limits spur creative, makeshift entertainment within their apartment complex.

Characterized by a polite and benevolent nature, Yurume possesses a distinctive visual trait: symmetrical hair buns. Across the OVA and "Yurumates 3D" television series, she remains an earnest yet unobtrusive presence, sometimes overshadowed by more assertive personalities in the group. Her key development arc involves adapting to communal living, where her initial rural naivete gradually blends into the boarding house's collective identity. Relationships evolve through shared financial struggles, humorous exploits, and mutual support, fostering a camaraderie that often takes precedence over academic focus. The narrative highlights her integration into this micro-community, where interpersonal bonds and shared experiences ultimately define her ronin year more distinctly than exam preparation.