Exterior

Exterior (外装代脳(エクステリア)) is apparently some device that greatly boosts Shokuhou Misaki's power from several hundred meters range and absolutely controlling a maximum of 10 people (or from about 100 people as long as they are doing simple commands) to a range of several kilometers, allowing her to put thousands of people under her control.

Daihasei Festival Arc

 * Main article:Daihasei Festival Arc (Railgun)

Misaki can apparently issue Exterior commands in order to greatly increase her mind control abilities. In chapter 59 of the Railgun manga when this is first seen, Mikoto Misaka, who was with Misaki at the time, thinks that the powers granted to Misaki by Exterior far surpass the abilities that a level five should be able to use. It seems as if Shokuhou does not like to rely on the use of Exterior. Moreover, during her command, a small panel of eyes overlayed upon a background filled with liquid and tubes are briefly shown, indicating that it is at least human as the eyes displayed the properties of being controlled by Misaki.

Agitate Halation Arc

 * Main article:Agitate Halation Arc

At some point during this arc, when Misaki reveals to Touma the extent of her powers, she makes it clear that she does not have the increased abilities that Exterior allows her to use. She does not explicitly mention Exterior at all.