Alter ego of Natalia "Natasha" Vasylchenko, the member of the inner circle of Zvezda. She is the main technology expert of Zvezda and also responsible for the maintenance of their superweapons and the HQ.
She was separated from her parents by unknown beings she called "fairies" and rescued by Kate. Her parents seem to have a connection to whatever force stood behind the governor of Tokyo, Kyoushirou Jimon.
Etymology: Um/Ум is Russian for "mind".