Hazuki Yuiga is the younger sister of Nariyuki and Mizuki Yuiga, and the older twin sister of Kazuki Yuiga. Her full name is written as 唯我 葉月 (Yuiga Hazuki), with surname Yuiga signifying "solitary" and given name Hazuki combining the characters for "leaf" (葉) and "moon" (月). The name Hazuki traditionally references August, interpreted as the "month of leaves" or historically as the "month of falling leaves".

She possesses brown hair styled in pigtails and aubergine eyes. Alongside her twin brother Kazuki, she frequently teams up to play matchmaker, attempting to pair their brother Nariyuki with various female acquaintances.

Her narrative presence remains unchanged across all documented official media, steadfastly maintaining her role as a supportive family member centered on lighthearted exchanges with her siblings.