Karen Kōzuki (紅月カレン, Kōzuki Karen) is a Britannian-Eleven girl, who believes herself to be a Japanese person at heart and prefers to be known by her birth name. She comes from a prestigious Britannian family and attends the Ashford Academy, where she is a member of its student council and amongst its most outstanding students. Her brother, Naoto Kōzuki (紅月ナオト, Kōzuki Naoto?), with whom she had a deep connection, was a former leader of the resistance organization and died in the past.

Rider is a fictional character from the Japanese visual novel and anime series Fate/stay night by TYPE-MOON.

She is the Servant of Shinji, first seen scouting around Homurabara Gakuen. Rider is silent, sultry, and vigilant, never hesitating to shield her Master from harm. Her weapon of choice is a pair of long iron nails fastened to opposite ends a single chain, which she effectively thrusts from distances.