Yui Kōriyama, a married woman portrayed in the narrative, forms a complex relationship with Tsuyoshi, a college student central to the story. Her character balances a composed exterior with alcohol-fueled vulnerability, particularly when drinking chuhai—a canned beverage that triggers shifts into flirtatiousness and emotional exposure. Promotional imagery underscores this duality, depicting her clutching a chuhai can adorned with subtle visual motifs of Tsuyoshi. Interwoven into an omnibus structure where Tsuyoshi interacts with multiple married women, Yui emerges as a recurring figure. One narrative arc frames her as a "strict aunt" whose authoritative demeanor dissolves after alcohol consumption, contrasting rigid propriety with unrestrained behavior to drive tension in her interactions. A dedicated volume, *Full Color Strong Edition Marugoto Koriyama Yui*, showcases her narrative prominence, framing her nocturnal experiences through a lens of warmth interlaced with intense passion. While explicit backstory remains unexplored, her role dissects themes of escapism and relational intricacy tied to marital discontent. Her development across adaptations remains undefined, as the anime’s July 2025 release approaches alongside the ongoing manga. Existing portrayals position her as a conduit for examining adult dynamics, with alcohol serving as both a narrative catalyst and symbolic bridge between restraint and desire.