|“||Now that I know where that robot will be, I can destroy MECH-X4 in front of it's biggest fan.||”|
— Principal Grey
Principal Kim Grey was the principal of Bay City High. She appears nice and caring, but in fact is the one deploying the monsters against the city. She is working for Seth Harper, an evil mastermind bent on destruction, but she never knew her boss's identity.
She is portrayed by Ali Liebert.
She appears to be nice, but is actually the one behind the monster attacks. When one of the monsters she created lost a battle to MECH-X4, she became extremely angry, showing that she has a short temper.
- Monster Desk: Principal Grey has a desk located in her office which allows her to merge two creatures or creatures' D.N.A. together to create a monster. It glows orange when in use, just like the goo the monsters are made of.
- Ninja Skills: Principal Grey is very flexible and very good at combat fighting. This was shown when she fought Ryan in Let's Open The Monster Heart!.