Project 153, or 153 is an enemy bio-weapon who is the central antagonist in Thing-Thing 3, and returns in 4. He is stylized with long, red hair and coat, along with black plain shoes. Later on he is updated to wear metal-plated boots, and eyeliner.
Along with your avatar, 153 is part of a series of infantry experiments, later seen to be the only other completed project from the System Corporations' secret bio lab. He was engineered as a pilot, and is never seen engaging without using a mecha. Outside of machines, he appears to have authority over the company's ground forces, organizing mercenaries in pursuit, and cornering you with a platoon.
He seems to bear a personal grudge against 154; often taunting that he is superior, and finds alternative ways to fight, such as activating Vahl Dreig.
Compared to your avatar, 153 is less capable physically, but shows clever planning capabilities; as he lures you to an industrial sector of the city, which leads to a secret passage to a System Corporations research facility. He prefers to engage indirectly as a result of his pilot nature, using a mobile suit and a helicopter during confrontations. This may demonstrate that he is able to quickly adjust to different types of machinery.
After escaping from the facility's head office, 153 flies a helicopter to your position. Finding a car and light machine gun nearby, you give chase around the city. After its gas tank blows up from constant gunfire, the helicopter crashes onto the ground and 153 is killed in the following explosions.