It is shown that C-ko is a bad cook. Her homemade lunches usually have one big problem: they're WAY too spicy. On at least two occasions, people have literally breathed fire after eating some of the lunch (C-ko herself one of them), but she proudly offers it to A-ko anyway, each and every day.
C-ko is the object of A-ko and B-ko's bitter rivalry. B-ko wants C-ko for herself, but A-ko is not willing to let her do that. There's the problem of those aliens from outer space who claim C-ko's their long-lost princess, which turns out to be true. Yet C-ko doesn't really care. All she really cares about is A-ko. She's happy when they're together, sad when A-ko doesn't look all right, wailing when A-ko insults her, and angry when A-ko doesn't pay attention to her. This doesn't mean she hates B-ko, she just likes A-ko more and is loyal to her. In the end, she wants to see an end to the fighting.
C-ko is 17 years old, stands at 5'1 tall, and weighs about 95 lbs. She does not have any special powers or abilities, making her the most ordinary of the three, despite her alien ancestry. She is the Fourth Princess of the Fifth Queen of the Kingdom of Lepton, and she is from the Alpha Cygnan race.