Fubuki Amatsuka is the twelfth of nineteen sisters. This seven-year-old attends second grade and possesses light pink hair along with pink or purple eyes, standing 128 centimeters tall; her birthday is September 21. Fubuki consistently maintains a stoic, expressionless demeanor, often delivering remarks—including those of a sexual nature—with a straight face. Despite her young age, she exhibits high intelligence and strong comprehension, frequently applying knowledge from books or other sources by conducting experiments on her adoptive older brother, Yotaro, for whom she harbors affection and uses as a subject for observational or educational activities. She shares a close association with her younger sister Watayuki, the thirteenth daughter, and they are frequently seen together during family activities. Fubuki participates in group events like a family river outing, where her calm and detached behavior contrasts with the more energetic personalities of her siblings.