Wistful Amnesia

"There's not a word yet For old friends who've just met Part heaven, part space, Or have I found my place?"

- Gonzo, The Muppet Movie, "I'm Going to Go Back There Someday"

Characters whose memories are wiped of certain events may retain the sense that they've lost something.

If that sounds unfulfilling, no worries. The character will often recall their memories through some token gift or heirloom left behind. They will then reunite with their lost comrades.

This is probably the most tolerated version of the Reset Button. The Aesop of this trope is usually that everything and everyone's connected, and even if you can't remember a friend, there will be a part of you that will never be the same without them.

For obvious reasons, this occurs in shows with a mystical or fantasy element, although science fiction shows can do this if they have memory-erasing Phlebotinum available. Compare Amnesiac Lover, where a present romance is forgotten.

Anime and Manga

 * Subverted in the OVA of Ah! My Goddess, where Belldandy is required to set up such an effect as part of her recall to Heaven; this is cancelled when the damage to Yggdrasil is repaired.
 * Rukia's existence is wiped this way when she is captured in Bleach—the only people who remember her are her True Companions. It is implied that Ichigo still vaguely remembers Senna at the end of the first movie.
 * Code Geass:
 * Lelouch uses his Geass to alter the memories of a classmate who happened to find out his role as the terrorist Zero. Psychological torture at the hands of one of his enemies left them emotionally devastated and very nearly homicidal/suicidal, so he erased all memories of himself from their mind (not just his identity as Zero). Humorously enough, everyone else at school can't seem to understand why has forgotten him, and Lelouch convinces them that the whole thing is an act the amnesia-ee is putting on because they're angry from an argument with him.
 * In the second season,
 * In the first season finale of Keroro Gunsou, Fuyuki remembers Keroro after finding and building a Gundam model he left in the basement.
 * In Neon Genesis Evangelion Angelic Days, Kaworu is forgotten once the school year ends, and any sign of his existence disappears, but Shinji knows that someone very important was supposed to be in a certain place in a picture. However, he never remembers Kaworu, even in the Distant Finale in which Kaworu meets him one last time (or for the first time, as far as Shinji knows.)
 * In Petite Princess Yucie,  gets struck with this when   gets better.
 * Similarly, Kei remembers Mizuho in Please Teacher by her trademark box of pocky.
 * The final minutes of Revolutionary Girl Utena indicate that this effect is overtaking almost the entire student body of Ohtori Academy, leading them to forget Utena ever existed. The positive changes she had on them, on the other hand, didn't seem to fade.
 * The first season of Sailor Moon ends with Usagi's wishing that she and her friends were just normal girls, and having it by the power of the Ginzuishou.
 * In Serial Experiments Lain Lain.
 * Tenchi Muyo
 * This happens in Tenchi In Tokyo: at one point, all of Tenchi's classmates forget Sakuya ever existed, and her name is erased from the school catalog.
 * One short arc in The All-New Tenchi Muyo has Washu's Evil Twin force Washu to make the rest of the cast forget about her. Ryoko's clone, Minaho, was unaffected (due to the fact she was off-planet) and is able to get everyone to realize something's wrong. Washu restores Tenchi, Ryoko, Ayeka and Mihoshi's memories (though, Tenchi's very displeased she removed them in the first place), but Sasami remembers on her own.
 * The World God Only Knows revolves around the protagonist, Keima, driving evil spirits out of their hiding places within girls' hearts by making the girls fall in love with him. In order to maintain the Masquerade, the Underworld removes everyone else's memories of the seduction. The targeted girls retain the Character Development gained through their experiences, however, and tend to blush around Keima without knowing why.
 * in that not all of the girls
 * Another girl eventually
 * At the end of the Venus Versus Virus anime, . Averted in the manga though.
 * Although it's (probably) not intentionally induced, 's amnesia at the end of Weiss Kreuz Gluhen functions in precisely this way, removing him completely from the underworld that Kritiker and Weiss occupy and allowing him to start a normal life in which he doesn't have to be an assassin. Sequel manga Weiss Side B makes the "wistful" part a little more overt with a flashback appearance:.
 * Homura shows signs of this for at the end of Puella Magi Madoka Magica.

Comic Books

 * In House of M, characters who used to be heroes are now mundane and struggle with a sense of loss. Doctor Strange, now a psychologist, spends time counseling Robert Reynolds, aka The Sentry, who doesn't know what he's lost but he's certain he used to be more...
 * Spider-Man: Brand New Day: This is why Mephisto agrees to swap Aunt May's life for Peter and MJ's marriage. His payment is the mourning of the small part of their souls that remember what was.

Film -- Live-Action

 * Eternal Sunshine of the Spotless Mind: "Meet me in Montauk..."
 * Agents who retire in the Men in Black series have their own memories erased via the same memory-wiping technology they use to keep normal folks from learning that aliens exist. We find out, though, that even mindwiped, Agent K made a mess of his life because he couldn't put aside the changes his MIB lifestyle had left in him.

Literature

 * At the conclusion of The Dark Is Rising series, this form of amnesia is inflicted upon, as their destiny is to live in the mortal world and leave memories of the (now concluded) conflict between the Light and the Dark behind. However, Merriman tells them that they may still remember the supernatural world in dreams, and they will always carry with them a sense of the wonder that is now past.
 * This happens in Dokkoida after the hero's memories of the series' events are erased.
 * Literary example: the Mennyms books by Sylvia Waugh are about a family of life-size rag dolls attempting to live like normal humans without being found out. In the second book, the ghost of the woman who made them drafts in her nephew, an ordinary man, to help the Mennyms when their house is threatened with demolition. He falls in love with Pilbeam Mennym, but is given amnesia at the end of the book, the stated reason being that their relationship could never work since Pilbeam will never get any older. The family certainly could have used his help in the next three books. When he returns later in the series he is married to a woman who subconsciously reminds him of Pilbeam, but even though he sees the Mennyms again he never finds out that he knew them before or that they are alive.
 * The first Tennis Shoe Adventure book begins like this, then has Jim, the main character/narrator find an old story he wrote, which gives an explanation(in story) that if he ever told, he'd forget. the next book has him remember the story.
 * In the Young Wizards books, it's said that this is what happens to wizards who give up being wizards.

Live-Action TV

 * Doctor Who and the Whoniverse:
 * In the two-parter "Human Nature"/"Family of Blood" the Doctor's personality and memories have been wiped, replacing it with that of average school teacher John Smith. Despite being decidedly average, Smith displays the occasional feats of bravery, and has strange dreams of "the Doctor" and a blue box, which he writes stories about. His love interest Joan Redfern speculates that this is the man he wants to be. Subverted, however, that when he realises the truth, he's absolutely terrified by it, and wants to remain himself.
 * Professor Yana in "Utopia", a man who is one of the most brilliant scientists ever, but stuck at the literal end of time, unable to truly realise his greatness.
 * And.
 * Amy's storyline for the last few episodes of her first season involved this. Even after her fiancé is wiped from existence, and she retains no memory of him, she still finds herself crying, unable to understand why.
 * Gwen in the Torchwood episode "Everything Changes". She manages to piece together her memories though.
 * In the last scene of Kamen Rider Ryuki's  finale,   accidentally bump into each other outside of Atori. They squabble a little, and presumably leave with bad impressions of one another, but before going their separate ways, take a short moment to glance towards the other's way.
 * Lost's season 6 flashes show the characters having forgotten one another . Triggers restore everyone's memory, and they reunite.
 * In Once Upon a Time, all the fairytale characters lose their memories and get sent to the real world, and several of them experience this.

Tabletop Games

 * Changeling: The Dreaming:
 * This is the result of a changeling succumbing to Banality or having their fae mien destroyed in a way that doesn't harm their mortal seeming; with their ties to the Dreaming severed, they have—at best—hazy memories of playing "make-believe" as children and generally don't remember anything at all. They often have a feeling that "something's missing," though, and are more prone to depression than one might expect. Those who are still part of the Dreaming remember them clearly.
 * This also applies to Bedlam, too, but only to in the first stage, where the afflicted will often self-treat by leaving the fae world temporarily, and taking up a very Banal existance; this is the only one that works in the typical Reset Button way, in that the character will remember and return to their friends after a while - being overcome by Banality generally requires large infusions of glamour to fix - if there's enough left to fix - and having their fae mien destroyed almost always leaves the character beyond recovery.

Video Games

 * Kingdom Hearts II
 * The beginning uses this trope on Sora regarding Roxas's friends in Twilight Town. Although he does have an item of Roxas's, in a small subversion, he never does remember them directly, although he does learn Roxas's story.
 * Roxas himself manages to avert this, though. He knows he doesn't remember his old friend Axel, but for the most part, he really doesn't care. He's more angry that Axel keeps butting into his new life and throwing it all into chaos. The old memories are only reawakened despite Roxas' best efforts. And it still takes a long and rocky time to
 * On the other hand, Roxas plays it totally straight in the case of.
 * This also applies to Sora's friends before he wakes up. Kairi in particular is living this trope: she knows there was a boy who was very important to her, but can't remember anything else about him, and this bothers her so much she refuses to return to the small island where they used to play until she can remember everything. Riku has the same thing to a lesser extent—only "fogginess" instead of outright amnesia, thanks to the exact mechanics of the magic involved.
 * Completely subverted in Chain of Memories: Early on, Sora realizes he has forgotten a second girl he was friends with on Destiny Islands, including her name, and struggles (and succeeds) in remembering more and more about her..
 * Xemnas gives the series a villainous example. He only recalls about a year of his human life, and one of his biggest goals—even as a Chessmaster and Magnificent Bastard of literally world-destroying proportions—is simply to find the old friends he can't quite remember.
 * The entire main cast of Persona 3 (barring Aigis, who is a robot and can't be magically mind-wiped) lose all their Dark Hour-related memories in both endings—which include basically most events of the game, including lots of Character Development, the true nature of the deaths of several significant ones and the cast's memories of each other as True Companions. In the 'good' ending, it even, and the main characters recover their memories on graduation day in a classic subversion. In the bad ending... They don't. And at that point it wouldn't matter to them even if they did.

Visual Novels

 * The bad ending for attempting to access the Unlimited Blade Works route too early in Fate Stay Night is like this, with Rin forcibly erasing all of Shirou's memories that magic exists and breaking his contract with Saber. The ending features Shirou going about his daily life as usual but with the occasional feeling that there should be more people living with him; the only person close to him that knows the truth gently convinces him that he's just imagining things in order to protect him.
 * Several examples in Princess Waltz. But the biggest is when Riko, Chris and Liliana all magically disappear from the class and are essentially forgotten. Nodoka stresses a little bit about this as she can't remember them, but knows the class is smaller than it should be and has a small remembrance of the people who are gone.

Webcomics

 * In The Wotch, a teacher is turned into a teenage girl by one of the many Annes running around, and when s/he runs after her (and into a different Anne who doesn't know what happened) and says s/he can't live as a man with the body of a teenage girl, this other Anne fixes it... by giving him/her the mind of a teenage girl. The "new student" joins the cast, never suspecting she used to be a different person with a different life, but joins the club that's researching the strange happenings around town because she wants "to remember." The other characters figure it's her shaky English and she meant "learn," especially when she realizes she doesn't know what she meant.

Western Animation

 * In American Dragon: Jake Long, the original series finale, the episode called "Homecoming", remade the timeline so Jake's love interest/villain's sidekick Rose never joined the Huntsclan, and thus had no memory of him. When the series was extended by an extra 13 episodes, the plan was to have Rose be in school without knowing Jake or anything about the magical world, and to have Jake try to woo her again from scratch. Disney execs vetoed that as too confusing and too arc-based for reruns, and thus Rose's family packed off to Hong Kong immediately after she meets Jake for the "first" time. Jake wishes her the best and gets on with his life, but the as-yet-unaired actual series finale is called "The Hong Kong Longs", meaning a Last-Minute Hookup is still possible.
 * One episode of Darkwing Duck involves alien invaders whose princess needs help overthrowing the Evil Chancellor. Afterwards Darkwing and Gosalyn have their memories wiped. What about Launchpad? He and the princess are friends from way back, so they don't wipe him.

Real Life

 * A particularly depressing case of Truth in Television, Alzheimer's tends to invoke this a lot in its victims.
 * Another example: Korsakov's syndrome
 * More Truth in Television: this is central to the concept of Sehnsucht, which describes a sort of bittersweet longing for something one can no longer identify or describe.