Dr. Hal Emmerich , nicknamed Otacon due to his fondness of anime, first appears in Metal Gear Solid as an ArmsTech employee who designed Metal Gear REX. After being rescued by Snake from the Ninja, he begins to assist him after he realizes that REX is being used by the terrorists to launch a new type of nuclear warhead. Kojima states that he created Otacon as his way of glorifying the otaku stereotype by having a character who fights the terrorists with his intellect rather than his brawn. According to Kojima, the original idea of Otacon was to make him "heavier, wearing a cap, and programming while eating a chocolate bar". However, the design Shinkawa did for the character was a slender one instead.
