Candice Moore

There is a war going on between masters and servants in order to attain the Holy Grail. Each master can call up one servant each, and their task is to eradicate the other servants, either by defeating them or killing their master. When there is only one master or servant left, he or she is granted the Holy Grail, and any wish they desire will come true. (imdb)

Sachiko, the most popular girl at her new school, has offered to be Yumi's soeur, or "sister", and guide for all her years at the academy. Yumi is flustered because she is unfamiliar with the tradition, the school, and Sachiko.