Naokaoji's little sister, who summons Raz in order to get rid of her big brother once and for all so that she talk to the boy she likes and start using her cellphone again. She calls Raz "Demon", probably because of the way they met (via summoning). It isn't actually known what happens to her after that, however there is a woman that looks a lot like her on the last page Raz appears in. If it is her, more than likely Umi decided to further her interest in magic.