The main characters in Metal Gear Acid 2.
His identity is unknown, though he claims to be a college student. A self-proclaimed genius hacker, who will only get involved when his curiosity is triggered. His seemingly flip motivations counter-balance his great intelligence.
He is the FBI agent that arrests Snake and forces him to help in the investigations of SaintLogic. Dalton is a very passionate person, he would never admit to saying that the law must be bent, in order to protect it.
 Doctor Koppelthorn
Doctor Koppelthorn is the Vice-President and the head of Research at SaintLogic Inc. He specifically leads the Weapons Development Division. Koppelthorn also has special authority over the development of EGO, the central control system. He was the one who set off the chaos at SaintLogic when he used his own creations... Metal Gear.
 Doctor Takiyama
A researcher working under Koppelthorn. She performs experimental surgery on variety or living things as test subjects. She always performs research herself, though she lets people handle peripheral task. Her personal affairs are in complete disarray. She often reports deliberately wrong information to the company President because she resents his lewd glances.
A mysterious and young girl who is under Doctor Takiyama's care.
Snake fought in the Resistance over three years ago for an unknown reason. While making his way back to the United States, he was captured by the FBI and forced to take part in this mission. He has fully developed combat skills from his long career as a mercenary and is adept with all kinds of firearms.
A female soldier who reports directly to the Defence Department’s mission leader, Wiseman. Her primary objective is to control the chaos at SaintLogic Inc, not matter the means. She is a loner with no apprehension about lying or killing and seems incapable of understanding the ideals of right and wrong.
A cold hearted man who does not see eye to eye with people. He hugely believes in the justice system although he has admitted that it’s not as efficient as he would like it to be. He is the person who seized Dalton's ship in order to put down the chaos at SaintLogic Inc. His motives for this are still unclear.