Dr. Kyoko Nezumi is a cruel giantess scientist with a sick fascination for experimenting on humans and the cities they live in. At nearly two kilometers tall, she does not see a city as a place full of people, but as a crunchy and fragile little testing ground. Streets, buildings, soldiers, vehicles, and civilians all become disposable pieces in whatever experiment she has decided to run that day.

Because of her colossal size, Kyoko is practically immune to anything humanity can throw at her. Missiles, tanks, aircraft, and warships barely register as more than minor annoyances, making her impossible to stop once she chooses a city as her scientific playground. The question is not whether destruction will happen, but how much of the city will still be there when she gets bored.

Kyoko is cold, sadistic, distant, and horribly condescending, though she usually hides it behind the calm manners of a researcher. She likes to pretend her work has some higher scientific purpose, but most of her experiments are just excuses to scare, torment, and crush helpless humans while taking notes as if any of it actually matters.