An Entry Plug (エントリープラグ) is a capsule-like tube that houses the pilot in the Eva. It acts as the cockpit for the pilot. Entry Plugs are inserted into an Evangelion's spinal area via a loading mechanism, after which it spins inward and locks itself firmly into the Eva's torso. The standard color for the most used Entry Plugs is white, however, the ones controlled for the Dummy Plug system are red. Plugs appear to be extremely resistant to damage, as can be seen with the Unit-00's entry plug, which survived the Eva's explosion.
The standard entry plug is white with its respective Unit's number printed near the end. The plug is entered via a hatch that opens above the pilot's seat - to the pilot's left, there is an additional square emergency hatch. The internal control system is fairly standardized among entry plugs, consisting mostly of two hand held devices with at least three visible triggers, with the exception of Provisional Unit-05 which has many more. These handles can be detached at one end to become similar to joysticks. The visual interface differs slightly between units: Unit-01's entry plug has a single continuous screen while Unit-02's has clearly segmented front and side views.
Signal Termination Plug
A Signal Termination Plug is used while an inactive Eva is stored instead of a Standard Plug, and is an additional measure to prevent an Eva from starting on its own. The end of the Signal Termination Plug, which sticks out of the back of an Evangelion, is shaped like a crucifix.
The Signal Termination Plug is most prominently seen in Episode 02 and Episode 05, when Evangelion Unit-00 is frozen in bakelite after it lost control during an experiment. However, a Signal Termination Plug is seen again (very briefly and in a dark shot) in Episode 11, when it has to be manually removed from an Evangelion so that an Entry Plug can be loaded in.
This device is often referred to by a number of other names "Stop Signal Plug", "Termination Signal Plug", "Terminator Signal Plug" and "Signal Terminator Plug" being common variations in naming.
The Dummy Plugs in the main series are red with their type name ("Rei" or "Kaworu") printed on the side. Dummy Plugs in the Rebuild continuity are more stylized - black with criss-crossing white lines, with identification becoming apparent only when the plug takes control and displays the words "DMYSYS Golgotha Base Built" on the screen.
The method of control varies greatly. How the original Dummy Plugs function is still a mystery, but their actions are based on the thought patterns of either Rei Ayanami or Kaworu Nagisa and seem to have a connection with the soulless Rei clones which apparently make up their "core". When these plugs take control the pilot is still aware of what their Evangelion is doing, but unable to do anything about it as the controls become unresponsive.
Those in Rebuild series seem much more mechanical in origin. When activated, a large, vaguely humanoid structure rises from the back of the pilot's seat, hunching over them and locking the controls with two long black arms, stopping the pilot from moving the controls. The interface screen goes blank as the hunched figure displays its own screen message whilst assuming complete control.
The seat of an Entry Plug can only go to a certain allowed point, normally only middle - back section of the plug. While the cockpit is being monitored, there will be times where the seat, along with the pilot, will go too far down into the plug. This is known as "Negative Values". Apparently, going down too far down the plug will cause the pilot to lose humanity, as stated when Misato orders to forcibly eject the Entry Plug to save Asuka in the possessed Eva-03.
- Evangelion pilots can actually enter, then activate, an Eva entirely without external aid if they need to. Although there is a dedicated Entry Plug loading mechanism in NERV HQ, a pilot can manually open it. This is seen in Episode 03 when Shinji admits Toji and Kensuke into the entry plug, and in Episode 08, when Asuka triggers the release of Unit-02's Entry Plug by use of a mechanism on the side of the Entry Plug's hatch. The pilot can then launch entirely independent of the control center.
- In addition, the image of "inside a mother's womb" can be taken from the entry plug that Shinji can't escape from, and the image of "giving birth" can be taken from the scene where Unit-01 escapes from within the Angel, covered in blood. Thus, this is also an episode with strong symbolism. - Platinum Episode Commentaries