Yuri serves as a Third Grade Armed Librarian at the Bantorra Library and is the younger sister of Yukizona Harumi, a First Grade Armed Librarian and candidate for Acting Director. Hailing from a noble family, both siblings occasionally display arrogance. Yuri openly regards herself as superior to others and expresses her opinions without restraint, though her haughty demeanor is often undercut by a significant naivety and lack of world experience.

She possesses a temporary healing ability, which she uses to alleviate her brother’s chronic and debilitating illnesses, though it provides only momentary relief rather than a cure. Yuri places her trust entirely in Yukizona, and their relationship is defined by a deep bond of mutual reliance.

A skilled combatant specializing in firearms, Yuri demonstrates mastery over weapons ranging from small machine pistols to large anti-aircraft artillery. In battle, she fires with wild, berserker-like intensity but never misses her targets. She also exhibits a passive healing ability, which she employs to restore her brother’s strength after his abilities leave him weakened.

Yuri has notably low alcohol tolerance; even a small amount causes her to abandon her refined demeanor and become unpredictably wild. She was among those aware of the existence of "Heaven," and once traded her winter coat for a transparent nightgown worn over black underwear.

Her story intersects with that of Daltom, a former Armed Librarian and Mock Man of Kachua who was lured into rebellion against the Bantorra Library and acted as an informant for the Shindeki Church. Daltom was responsible for the deaths of several individuals, including Vizac, Noloty, and Arkit.