Uruka Sumeragi

Best friend of Nako until Kurumi came along. Uruka is in love with Nako, and had originally hoped to be the one to take Nako's first kiss. On the day that Kurumi appeared, she was the first witness to see the fateful kiss, to which she could not get over for an entire day. Uruka now sees Kurumi as an obstacle to Nako and will try anything to remove Kurumi, even if it means asking her father to call upon the family's private army to take her down. When they find that Saki is a Steel Angel, the family army decides to use her as a weapon against Kurumi, the "source of Uruka-chan's unhappiness." On the day that Saki was to be awakened, Uruka was there to supervise the process, but got involved in a fantasy of her own, involving Nako, and ended up kissing Saki. Saki then falls in love with her new master, and Uruka wants nothing to do with her.

(Source: Wikipedia)