Asahi Amatsuka, the nineteenth and youngest daughter of the Amatsuka family, was born on April 15. During the story's events, she is approximately nine months old when protagonist Yotaro joins the household on December 25. Her zodiac sign is Aries, and her blood type is AB. Physically, Asahi has blonde hair reaching her ears, blue eyes, and stands 64 cm tall. Despite her infancy, she exhibits a mind of her own, displaying distinct preferences and reactions. As the baby of the family, she completes a lineup of nineteen sisters spanning from newborns to adults, with the eldest sister aged eighteen.