Kayko is Yusuke's closest (and at times, only) friend. She and Yusuke have known each other since they were little children, and although he would never admit it, she is probably the person that he cares most about in the world. As such, Kayko has a unique ability to talk sense into Yusuke when he is being stubborn or unruly. Kayko is one of the leading students in her school. Intelligent, friendly, and outgoing, she is well-liked and respected by her peers. She is confident, self-assured, and at times a bit head-strong. She is brave in the face of danger, and will not hesitate to put herself at risk in order to help a friend in need.