A device by which the audience or a major character (or both) gets a brief view of other major characters who have yet to appear in the story: an optical effect gives the sense of a moving tube or tunnel, down which translucent or opaque images of various characters swirl and recede. When not found as part of the opening credits, the Tunnel is usually the result of some mind-altering experience, such as the process of being TrappedInAnotherWorld.
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!!Examples

* Literal example: If you stand in the three tunnels to each island in ''{{Crackdown}}'', you can hear the bosses of those islands cursing you out.
* The opening credits of ''{{Pretear}}''.
* Similarly, the opening credits of ''ParallelTroubleAdventureDual'' has a brief tunnel-like sequence.
* Makoto's transfer to El-Hazard in ''Anime/ElHazardTheMagnificentWorld.''
* The very first scene in the ''Anime/ReadOrDie'' TV series.
* A character who appears in a single episode of ''Anime/NeonGenesisEvangelion'' appears for a split second in the opening credits of the series.
** Rei's appearance early in the first episode of the series might count as well
* In comic books, Professor Zoom's time-rips showed Bart Allen in the Kid Flash costume several months before he started wearing it.
* In ''Series/DoctorWho'' episode "The Parting of the Ways", [[AGodAmI temporarily super-powered Rose]] gets a glimpse of the Tenth Doctor (David Tennant) in a similar optical effect, several minutes before Eccleston's Doctor actually [[TheNthDoctor regenerates]] into him.
* In the opening sequence of ''WesternAnimation/{{Futurama}}'', a brief moment when the camera reveals a long tube (used for transportation) features many recurring characters, including Amy, Hermes, Dr. Zoidberg, and Zapp Brannigan, all of whom didn't originally appear until after the pilot episode.
* The openings for ''VideoGame/FireEmblemTellius''.
* ''VideoGame/TheLegendOfZeldaMajorasMask'' shows silhouettes of the game's various transformation masks flying past the screen after Link falls down a very, ''very'' long hole at the beginning of the game.
* The pilot for ''WesternAnimation/TinyToonAdventures'', "The Looney Beginning", had Buster and Babs open a trunk full of villains, many of whom they would encounter in later episodes.
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