Rikka is a medical doctor who work at the hospital of the city. She seems to be in her late 30s. She is the "mother" of Meta and is the legal guardian of Mayuki. Because she take care of her since 15 years, they've develop a special relationship, they love each other very much, like a mother and her daughter. She was always a student at the time of the disaster. At that time, she had cared for some survivors and remembered taking care of a very young boy with a baby whom she loved very much. She recognizes Yukito and tells him that she is happy to see that he has "grown up" well.