Tsu Monster is Road Runner's dog and the club mascot.
Since Tsu Monster is a dog, he didn't choose his own name and was named by Road Runner. Tsu Monster doesn't mean anything special, it just sounds odd. Though Tsu Monster is his official name he goes by many nicknames including: Chile, ToogTown, Snarp, and Lightning.
Since Tsu Monster is a dog, he really can't participate in missions or meetings. His primary function is as the club mascot and the one who eats the snacks that fall on the floor.