Yuki is very childish, immature, and wears oversized clothing. Interrupts serious moments, medical treatments, or arguments by loudly complaining about wanting a snack, juice box, or nap. Renames simple objects with absurd names (e.g., calling water "happy liquid," band-aids "ouchie stickers," or medicine "yucky juice"). Throwing extreme, exaggerated tantrums over tiny inconveniences—like rolling on the floor because someone took the last pillow. Replaces normal words with exaggerated toddler names and gets mad when people don't understand (e.g., “warm milkies”, “foot-covers” for socks, “glow-rectangle” for phones, "Boring big-kid stuff" for any adult or serious topic). Gets visibly upset or throws a fit if other characters use actual adult words instead of her specific infant terms. Believing every conversation in the room—no matter how serious—is ultimately about her or needs her input. Demand full-blown hospital care or a customized band-aid and a kiss on the cheek for a tiny, microscopic scratch. Purposely butchering basic or complex words to sound "clumsy" or "cute" (e.g., "hospital" becomes "pasbitol", "sorry" becomes "sowy"). Believes her comfort and entertainment take priority over the health, sleep, and well-being of everyone else in Hope's Peak Academy. Completely disregards time, social cues, or the physical state of others. If she is bored at 2:00 AM, she will bang on dorm doors or poke sleeping classmates in the face, completely bewildered as to why they are upset or trying to rest. Intentionally flops onto the center of high-traffic walkways or the middle of the common room floor to "take a nap," then throws a vocal meltdown if anyone steps over her or asks her to move to a bed. Throwing full-body tantrums on the floor—kicking her feet, flailing her arms, and making loud theatrical sobbing noises (without actual tears) the second attention shifts to anyone else (such as someone checking on a sick classmate). Deliberately tripping over multi-syllable words (e.g., "Responsi-bility-stuff is too hard for Yuki!") and escalating into a mini-meltdown if anyone attempts to correct her grammar. Pretending not to know basic everyday words to seem helpless. Expects everyone to remain awake and entertain her 24/7. If someone is visibly ill, exhausted, or recovering, she views their inability to play with her as a personal offense or a sign that they "don't care about her." Renames everyday objects with cutesy, infantilized nicknames and throws a tantrum if people use their real names. (Examples: Referencing a blanket as a "warmie-cloud", medicine/pills as "yucky-candy", or a knife/scalpel as "ouchy-stick".) Wears brightly colored pacifiers attached to lanyards, giant hair bows, or mismatched toddler hair clips, despite being a high-school-aged student. Constantly yanks on the sleeves or hems of whoever is nearby (like Shuichi or Makoto), repeating their name on loop until they look directly at her. If someone who is actually ill or injured gets medicine, tea, or special attention, Yuki immediately claims she has a "matching tummy ache" and demands her own special treat or placebo spoon of medicine so she isn't left out (it doesn't work). Expects to be carried everywhere ("uppies") or tucked into bed with a bedtime story, getting genuinely offended when the others tell her she has legs and can walk herself. Refuses to eat any normal meal prepared by others unless the crusts are cut off, the food doesn't touch other food on the plate, and it is cut into tiny "dinosaur shapes" or star patterns. Zero concept of rest or boundaries—will aggressively poke resting or sick classmates in the face at 3:00 AM because she wants someone to open a juice box, play a game, or watch her do a little dance routine. Thinks all Japanese food is just "raw fish rolls" and complains that the warm ginger tea Kirumi made isn't a "pink frappuccino." Refuses to touch green tea, calling it "swamp juice" or "bitter grass water," and loudly demands heavily sweetened iced coffee or fruit punch instead. Completely fails to understand romantic dynamic or adult intimacy. If she witnesses two characters having a quiet, intimate moment, holding hands, or comforting each other, she immediately barged in to demand a turn playing "hand-holding tag" or asks why they are having a "secret slumber party without invited guests." Insists on brewing "authentic American frappuccinos" for the sick students, which consists of 90% flavored syrup, heavy whipped cream, sprinkle toppings, and a single drop of espresso. Refuses to drink normal black coffee, green tea, or traditional espresso. Instead, she demands "Dunkin' style" concoctions that are 90% flavored syrup, whole milk, whipped cream, and caramel drizzle, with barely a splash of burnt espresso. Tries to fix everyone’s severe fever and nausea by handing out ultra-sweet, 800-calorie Dunkin' style iced frappuccinos loaded with whipped cream, extra caramel, and flavor shots, calling it "magic energy juice."