Pre-Meeting

That's her new teacher she's manhandling.

The main character runs into someone out of the blue. The next day, (usually at school or work) they think of how they'll never see this person again, when the teacher announces they have a new student... guess who? This can be considered a very shallow form of Foreshadowing. Whenever a work takes the time to show someone "accidentally" bumping into a random character, you just know they're not random... and the "reveal" is usually only 5 minutes away at most, anyways. Sometimes it's done so that the main characters can have a different first impression of each other than the rest of the cast, who simply go by a "oh, it's just a new student" attitude. In a Harem Anime it can often be used to establish the Official Couple from the beginning.

Used most often in romance stories, but it doesn't have to a love interest; they can be a rival, mentor, employee, or whatnot.

Compare Meet Cute, a sub-trope where a (future) couple meet in an unusual way and will obviously fall for each other in the future; and Chekhov's Gunman, a character who is introduced but only gradually revealed (or re-introduced) to be important to the plot much later. Also see Early-Bird Cameo.

Examples of Pre-Meeting include:

Anime & Manga

Bleach: Ichigo absorbs Rukia's powers when he meets her, the next day she shows up pretending to be a student and tells him he has to take over her job temporarily.
Freezing: New student Kazuya mistakes Satellizer for his dead sister, causing her to lose a fight. Also accidentally runs into a Rana in town, who happens to be transferring into his academy.
Great Teacher Onizuka: Prospective teacher beats up a pervert who is feeling up a woman on the bus. Turns out both he and the woman are applying for work as teachers, and the pervert is the vice-principal...
Hen: Chizuru runs into Azumi in her boyfriend's apartment when Azumi first moves in, turns out she'll be attending the same school. Girls Love ensues.
Kiss Hug.
Love Hina: doubled up: Keitaro meets Naru 15 years prior, when they were little. He meets her again while looking at test scores. Then he meets her when he moves into the Hinata House.
Negima: Negi bumps into Asuna on his first day on campus, who mistakes him for a lost elementary schooler.
Neon Genesis Evangelion: Shinji meeting Asuka in the manga.
- And, in the anime, Shinji meeting Rei in the alternate universe/dream sequence.
Peridot: Akira, running from would-be rapists, bumps into Mahiru... who doesn't help her. Next day, at school...
In Sayonara, Zetsubou-sensei, Kafuka Fuura meets her suicidal teacher Nozomu trying to "make himself taller" before class on the first day of school.
In the softcore Hentai manga and anime Cinderella Express, a young man on his way to his wedding meets an attractive young woman on the train. It turns out that she's a hooker his friends hired as a "farewell gift." After some apparently very hot sex (windows are steamed over), the woman leaves the train a stop before the man's destination, and he figures he'll never see her again. The next day at the wedding, it turns out she's his new sister-in-law, and she'll be staying with the newlyweds until she can get a place of her own....
In Hanamaru Kindergarten, our protagonist, a male kindergarten teacher who is Late for School, sees a four-year-old girl standing alone by the side of the road. He stops and asks her, "Excuse me, ojou-chan. What are you doing here?" Ojou-chan essentially means "Miss" or "young lady" - not an unusual way to address a young girl one doesn't know. Anzu, the girl, has an active imagination, however, and immediately jumps to the conclusion that he's hitting on her. Naturally, he turns out to be her kindergarten teacher, and the misunderstanding persists. Hilarity of course ensues.
At the end of the first episode of ÉX-Driver, Lisa declares she's finally met her dream man after seeing his driving skills... and as he steps out of the car, it turns out he's a young kid. Then he shows up at her class, because he skipped grades and transferred to her school.
BeastMaster: Yuiko Kubozuka's pet cat climbs up a tree and is rescued by a mysterious guy. He runs away before she can thank him. The very next day Yuiko is shocked to find out that the mysterious guy's name is Leo and he's the new transfer student in her class.
Sailor Moon worships this trope.
- How does Usagi meet Mamoru, who turns out to be the re-incarnation of her lover in a past life and the phantom thief/superhero that shows up to save her neck at the end of the episode? By throwing a test paper into the air and accidentally hitting him with it. They don't have another "proper" meeting (in civilian identities) until the next episode, when she hits him with her shoe.
- She meets her feline mentor, Luna, by chasing a bunch of bratty kids away from a black cat they were beating up. While Luna initially runs off, she shows up later in the episode to stalk her and give her superpowers.
- She meets Makoto, who saves her from a bunch of delinquents on the way to school. Sure enough, Makoto is the new transfer student the same day and before the day is out, Makoto is Sailor Jupiter.
- Usagi meets her future daughter Chibiusa this way, with Chibiusa landing on her head after falling from the sky. Chibiusa runs away, and Usagi thinks nothing of it until she comes home and suddenly has a brand new cousin that she can't remember having.
- That hot young man Usagi meets suddenly and crushes on during the S season and "his" girlfriend? Sailors Uranus and Neptune.
- Chibiusa's meeting of Hotaru, who turns out to be both the major villain Mistress 9 and Sailor Saturn. Ironically, she actually traveled back to the past in this series because her mother told her she would meet an important person, essentially predicting this event.
Used several times in One Piece, especially with villains. Considering how crazy all the important characters look, it's pretty easy to tell who we will and will not be seeing again.
- During the Arlong Park arc, Arlong's foremen see Luffy walking on his own. They intercept his path, ask him where he's going, Luffy casually says he's going for a walk, and he... keeps going. About an hour later, they'll be killing each other.
- Mr. 2 Bon Clay ends up on the Going Merry for a little bit, and they spend the day dancing about the Okama way. Mr. 2 hasn't realized they're the Straw Hats, and none of the Straw Hats knew he works for Baroque Works.
- At Water 7, the crew comes across the foremen shipwrights. Several of them turn out to be CP 9 agents.
Rosario + Vampire begins with a Crash Into Hello between Tsukune and Moka. They walk to school together, but separate at the opening ceremony. Then it turns out they're in the same class.
Used to disastrous effect in Koi Kaze where Koshiro and Nanoka meet first on a train, go on a date together, THEN find out they're siblings.
In part two of Sweet Guilty Love Bites, the single mom Nina has a drunken night stand with another woman whose name she doesn't even bother to ask. The next morning, she discovers that that woman is her daughter's new preschool teacher. "Awkward" doesn't even begin to cover it.

Film

Confessions of a Shopaholic: Rebecca is on her way to a job interview and "absolutely must" have a new scarf for it. She stops at a hot dog vendor to get change so she can purchase the scarf "for her sick aunt". A nice young man hands her $20 so she can be on her way and he can get his hot dog. When she arrives at the interview, the man conducting it is.... none other than the nice guy at the hot dog stand.
In Grease, Sandy and Danny meet over the summer, but split ways as they assume that since Sandy's family is going back to Australia, they'll never meet again. Naturally, next fall, Sandy's family is now in America and she's a transfer student at Danny's school...
High School Musical pretty much rips off Grease with Troy and Gabriella meeting at a ski resort, singing a duet, and then assuming they'll never meet again...though this being a movie made and set in 2006, they swap cell phone numbers with the intent of keeping in touch. Which they strangely don't do, which leads straight to them having a surprise meeting at East High after Gabriella's family moves to Albuquerque.
Lake House (for Sandra Bullock's character).
In Dan in Real Life Dan meets Marie at a bookshop and the two have a natural rapport, although it turns out that Marie has a boyfriend. The next day, Dan's brother Mitch turns up with his new girlfriend... guess who! And UST Ensues...

Literature

Harry Potter: In the first six books, Harry always meets or hears about his new Defense against the Dark Arts teacher before school starts.
- The book 6 DADA teacher doesn't count because he had been teaching Harry a different subject for years. But the trend continues with the new Potions teacher.

Television

Crossing Jordan.
It's fairly common in BritComs for the protagonist to meet and insult somebody they think they'll never see again, only to discover that the person they've insulted is their new neighbour or work boss or bank manager etc.
Doctor Who companions frequently meet the Doctor like this. And in some cases, thanks to time travel, he arranges these events himself.
- In "Smith and Jones", Martha meets the Doctor when he approaches her in the street, takes off his tie and says "Like so!", and leaves. In the hospital where she's interning, she sees him posing as a patient but he claims not to know her. At the end of the episode, he proves that his TARDIS can move through time by time-traveling to the morning of their first encounter, then hopping out of the TARDIS while clutching his undone tie in his hand.
- In "Voyage of the Damned", the Doctor first meets Wilfred Mott as a newspaper seller in the otherwise abandoned London. Wilf turned out to be Donna's maternal grandfather. This actually happened due to Actor Existence Failure - the role of Wilf hadn't been planned during the special, but the actor playing Donna's father passed away early into the filming of series 4. His role was reworked into the character of Wilf and before the special with his small cameo aired, the credits were altered to change his name (he never said it on screen) to sync it up with series 4.
- In "The End of Time, Part Two", the Doctor, dying of radiation poisoning, travels back to New Year's Eve in 2005, the year he met Rose. He sees her on the street and pretends to be a drunk, telling her she's going to have a great year. Rose thinks nothing of it, presumably because thanks to time travel, the Doctor she actually met was the 9th Doctor.

Video Games

Final Fantasy VIII: Rinoa asks Squall to dance at the party, but doesn't think much of it. Squall's first mission as a SeeD is...
- Earlier in the same game: a "random" transfer student asks Squall to give her a tour of the Garden. The girl is actually party member Selphie. And a childhood friend Squall forgot about thanks to the memory loss he suffered from junctioning Guardian Forces.
Final Fantasy VII: After the first "job," Cloud runs into a girl selling flowers...
Final Fantasy IX: Zidane shows up to kidnap the princess and gets bumped into by a cute girl wearing a White Mage hood departing the castle.
In Persona 4, the main character meets a chatty gas station attendant at the very start of the game who shakes his hand. Turns out the "guy" is actually the goddess Izanami who orchestrates all of the strange murders in the game and gives the main character the power to summon Personas via this very hand shake