Natsuki Kruger

The headmaster of the Otome academy, she was schoolmates with Shizuru, Haruka and Mai. She is #2 of the Five Columns and is known as the Ice Silver Crystal. She is from the remote region of Count Kruger's territory. It is strongly implied that she and Shizuru are lovers. During her days as a student, she and Mai were rivals. She was Shizuru's room attendant, and later Rosalie's (Florence's Otome) onee-sama. Her Element is a massive energy cannon capable of executing an attack called "Howling Silver Wolf."

(Source: Wikipedia)