Rei Kujou (sister)
Yuu is a student at a fighting dojo run by a man named An, which may have been established to produce physically disciplined people for the creation of Guyborgs. He is first seen sparring with his sister Rei. Their practice is interrupted when Gou Kazama walks into the dojo, asking about his brother. Gou gets into a fight with Dojo master An. After Gou defeats An, Yuu asks him to replace him as their new master. Yuu has great respect for Gou, but will obey his sister before he obeys him.