Nanaki Moriyama

Nanaki is a classmate and friend of Illya, Suzuka, Tatsuko, and Mimi, later becoming close with Miyu and Chloe as well.

Generally laid-back, easygoing, and caring, she tends to avoid unnecessary conflict. However, Nanaki has a quick temper that often surfaces when something displeases her—especially if it concerns her older sister. This reaction highlights both her deep respect and protective feelings toward her sibling. Despite this, Nanaki is also forgiving and can be surprisingly tolerant once the issue has passed or if an apology is offered.

(Source: Type-Moon Wiki)