Alter ego of [[natasha_(sekai_seifuku)|Natasha resp. Natalia 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.

[spoiler]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.[/spoiler]

Etymology: Um/Ум is Russian for "mind".
professor um