The MICE (Micro-Intelligent and Cognitive Ectobrains) are the fruit of an experiment aiming for nanotechnology research.
Tiny three legged machines using brain cells to emulate real time decisions and behavior. The first prototypes used real mice brains.
One day, the research lab got assaulted by pro-life activists who set the poor things free. Little did they know was that the MICE got smart enough to recover the materials needed to build even more MICE units.
A few years later, MICE are now swarming the city like pests.

Kit ain't getting any of this. He often recieves calls from citizens asking him to dispose of mice lurking around homes. Those little things are pretty fast and annoying, which can make Kit lose his patience rather quickly. His boots might have been concieved for sneaking but they've also proven to work great as deadly weapons against micro-organisms.