Metal Gear Mk. II first appears assisting Gillian Seed in his JUNKER duties. Throughout the game, Mk.II's input becomes integral to the games progression, and its special functions are often used for information gathering purposes. For instance, the Mk.II can gather hair and tissue samples and perform DNA tests, and can also reconstruct faces referencing only the skull. Without Metal Gear at his side, Gillian's mission would have been much more difficult.