Tooko Murasame

Tsukumo's older sister, Yuki's relative and also a Zweilt guardian. Her ring produces a huge sword called Eon (Eternity). She attends the same high school as her brother, where their closeness makes all the girls jealous of her. She is very fond of Yuki (whom she calls Yuki-chan), telling him that "He is a person who is too kind for his own good" and asking him to refer to her in a more close way (Tooko-chan) instead of calling her Tooko-san. She is the guardian that most interacts with Luka, and sometimes blushes when is near him, which was due to the fact that in her past life, Tooko had a lover that resembled Luka.

(Source: Wikipedia)