Neco-Arc is a member of the Neco Spirit race, originating from the Great Cat's Village. She became Ms. Ciel's student, constantly acting up in retaliation for having such little screen time and wishing for people to think she is smart. Neco-Arc is known as the biggest small-fry in the Cat Kingdom. Most characters are unnerved by her appearance, and she especially torments White Len, calling her a "tsundere", and Satsuki Yumizuka, who Neko-Arc constantly reminds that she doesn't have a major role in Tsukihime. She recognizes Miyako Arima as a much-awaited future rival.