Yumi Totobami began life as a nameless orphan before the Totobami family adopted her to act as both caretaker and protector for Terano Totobami. Though initially bound by duty as servant and master, their relationship evolved into a bond akin to siblings. Yumi’s tanned skin, emerald eyes, and long blonde ponytail secured with a yellow flower clip contrast Terano’s paler features, while her rolled uniform sleeves and vibrant green nails underscore her relaxed demeanor. Eternally cheerful and energetic, Yumi’s buoyant personality offsets Terano’s stoicism. She openly prioritizes Terano’s needs, showcasing unwavering loyalty through actions like accompanying her to Hyakkaou Academy despite disliking gambling. Though she downplays her abilities, claiming physical strength as her sole skill, she aids Terano’s quest to dethrone Kirari Momobami through logistical support—pushing Terano’s wheelchair—and emotional reassurance, diffusing tension with humor. Self-doubt emerges during the Fascination Hall game when Kirari mocks Terano’s reliance on non-gamblers like Yumi, prompting her to question her worth. Terano’s affirmation of their kinship eases but doesn’t erase Yumi’s fears. To solidify trust among allies, Yumi hands a switchblade to housepets, permitting retribution if Terano betrays them—an act Terano begrudgingly accepts. When Moe Kijioka assaults Terano, Yumi instinctively shields her, defying her own aversion to violence. In subsequent conflicts, Yumi stays by Terano’s side, witnessing pivotal gambles and political schemes. Her attentiveness surfaces in moments like awkwardly consoling Miroslava Honebami or reacting to Sayaka Igarashi’s outbursts. Through casual quips and steadfast presence, she alleviates tension, grounding Terano’s ambitions in emotional vulnerability. While spin-offs and films explore her minimally, her core narrative role remains: humanizing Terano by embodying the loyalty and affection that temper her ruthlessness.