What Happened to the Mouse?/Anime and Manga

"George: *thumbs up* Yeah!
 * Sayonara, Zetsubou-sensei: Remember Kaere's split personality? She had a Yamato Nadeshiko personality in contrast to her Panty Shot, lawsuit-happy American personality. For all of 15 minutes. Sayonara, Zetsubou-sensei is three seasons in now, and it still hasn't shown up since.
 * In Yu-Gi-Oh! 5D's, third season character Sly, a friend of Ruka's from school, tried stealing Stardust Dragon and made that his personal goal by the episode's end. Nothing ever comes of this.
 * Ghost Hound:
 * In episode 7 of Soukou no Strain, Lavinia accidentally sneaks up with Jessie under the shower, thinking she is Sara. Jessie never appears to bring it up after that, which is weird, since she actually seemed to welcome it.
 * The battle that was being set up at the end also never evolves beyond a MacGuffin. For that matter, the war itself.
 * In an early arc in Yu Yu Hakusho, Yusuke and Kuwabara enter the running for the honor of being Genkai's apprentice, culminating in a tournament. During the tournament, two mystery contestants (the young Shaolin and Chimpo) face off in a completely dark room. We see nothing of the fight until the Shaolin comes back, and Chimpo... doesn't. He's never seen or referred to again, so no one really knows happened to him. His absence is so ignored by the other characters that "Nobody remembers Chimpo" becomes a Running Gag in Yu Yu Hakusho Abridged.
 * After Hiei defeats Bui, he leaves him lying in the stands, refusing his request to finish him off. Bui is never seen or mentioned again, although it's possible he died when Sakyo self-destructed the stadium. Similarly, Mitamura's three students are never seen again after struggling against Toguro's sucking souls to maintain his 100% form, without even any suggestion that they succumbed or survived.
 * Also, in the anime, the "nurse" of Team Masho, Ruka, who traps Hiei and Genkai in a barrier for the duration of that round, never shows up again after the barrier wears out. In the manga, she shows up in the epilogue going into an Earth modelling business with Koto and Juri.
 * The Digimon Adventure 02 episode "His Master's Voice". In this case, the cause was blatant Author Appeal: the writer for that episode is a huge H.P. Lovecraft fan and decided to randomly insert Lovecraftian elements into a series where it didn't fit, and didn't make any sense, and so they were never brought up again.
 * It wouldn't be quite as Egregious if the "Dark Ocean" introduced in "HMV" (Dagomon's Call or Call of Dagomon in Japanese) wasn't mentioned or revisited in... let's see... six more episodes, at least. But D(r)agomon is only mentioned once more, in episode-30-something. The questions still aren't resolved, though.
 * Same series you also never do find out what Daemon and associates actually want with the dark spores.
 * In the manga version of 02, Daemon is actually working WITH Oikawa, rather than against, and his purpose for wanting the seeds is explained.
 * Sunohara from Clannad, being the protagonist's best friend wasn't enough for him to play a major role or even appear more than just a few seconds in the later years of After Story, too bad for Tomoya his friend wasn't visible enough to help him face all those family problems; his only known feature during these harsh times, it's him working at some kind of a driving company.
 * Him and everyone else (Minus Kyou, who makes a cameo). Deus Angst Machina anyone?
 * Sunohara deserves a special mention because his status in the original Visual Novel; while the anime has all the girls together and some of their routes glued in despite the obvious Nagisa end, the Visual Novel is straightforward in making any girl not needed for a particular route disappear just like that, but Sunohara is present in all of them no exceptions thus is quite jarring seeing Tomoya suddenly not having his ever present friend when he needed him the most.
 * In the Kyou Chapter, all girls except for Kyou and Ryou seemed to have totally disappeared. Sure, the focus is Tomoya's blooming romance with Kyou, but does that mean his friendship with the others would just disappear like that? Same for the Tomoyo Chapter.
 * This is because both take place in alternate worlds based on their routes in the Visual Novel. His friendship didn't disappear, but instead never existed in the first place.
 * In the Naruto manga, there is a fight where Orochimaru summons two giant snakes. One is trapped in a swamp jutsu and later killed. The other injures Naruto and then is never seen again (not even as a puff of smoke which would indicate that it was de-summoned). The anime "corrects" this by having both snakes entrapped in the swamp; after attacking Naruto, the snake inexplicably sinks.
 * Summons in Naruto automatically return to where they came from eventually, so one can assume that's what happened to the second snake in the manga.
 * Another comes a little while later: Hayate Gekko, the proctor for the third part of the chuunin exams, is killed by Baki when he finds out about the Sand and Sound village's plan to attack Konoha. When his body is a found, a female ANBU member named Yugao Uzuki turns out to be Hayate's lover, and swears revenge. She's never seen again, and when Baki and the whole Sand village pulled a Heel Face Turn you're left wondering how she responded. One of the video games finally resolves the question, as if you start a match between Yugao and Baki, she will declare her desire for revenge at the beginning, and when using her special move.
 * The Akatsuki rings. Deidara, Orochimaru and Zetsu were all used to play up how incredibly important they were and the camera lingered tellingly on it a few times when Itachi first came to town. Not a single mention otherwise, and now that several Akatsuki members died with no indication their rings were recovered, there is no way that particular plot point will ever be visited again.
 * There's also Hanabi, Hinata's sister, who is supposedly stronger/more promising than Hinata (which is before Hinata Took a Level In Badass, so it's unclear where she stands now), and was possibly favored for inheriting the clan. Since the arc of her first appearance, she's yet to do so again to further the Hyuuga relations/hierarchy subplot. For Pain's Invasion, she is implied to be away with her father for an unknown reason, but while Hiashi reappears, Hanabi has not.
 * Speaking of Hinata, Naruto still hasn't gotten back to her about that whole "Declaring her love for him" thing.... Ticking off many many fans.
 * A minor example is Sasuke's Leaf headband. In their battle at the valley Naruto made an incredible fuss so Sasuke would wear it. After Sasuke leaves, one would think that an item, that represents his best friend's status as a Leaf shinobi, would be kind of important to Naruto and mentioned at least once during the long sessions of thinking about Sasuke in bed, but the headband was never shown again.
 * Naruto couldn't have known Sasuke dropped it, he was knocked out and Kakashi took him back. The headband might still be there.
 * It's used as a plot device in that filler arc with the tracker beetle, as the only item Naruto has that has Sasuke's scent
 * Ouran High School Host Club does this in episode 9. What happened to the PIT VIPERS? There were like 10 in that bucket, and then it just got tossed aside...
 * The very first scene of Tenchi in Tokyo features a pair of mysterious characters who appear in a flash of light, break into a shrine and steal a mysterious and seemingly very important box. Who are they? What's inside the box? Why are they stealing it? Your guess is as good as mine, because neither they nor the box are ever seen or mentioned again.
 * Speaking of Tenchi, in Tenchi Muyo!, when Sasami is introduced, she's seen with a ferret-like creature by her side. A few official works even show her with it. However, the creature's never seen again after Ryoko crashlands everyone back into the Masaki Shrine and is replaced by Ryo-Ohki. The compilation manga Densetsu no Sasami (Sasami Stories in America) have a set of comedic yonkoma that show the creature reappearing, gaining the name "Okiyama" and fighting a one-sided rivalry with Ryo-Ohki.
 * In Chobits first episode when Hideki finds Chii and carries her to his apartment, he doesn't notice a data disk that falls from her, the close-up we get to disk on the floor implies that it is something important but its never mentioned again nor it contents revealed. Another example where it's resolved in another medium; in this case, the manga has the explanation.
 * That was a bit more of an Aborted Arc; at that stage in the show, they were essentially copying the manga into anime form, but since the anime ended differently than the manga, they decided not to use the original purpose of the disc.
 * In Family Compo, Akane Fujisaki. She gets her own Story Arc, spanning several chapters. She appears in the first pages of the new arc and calls the main character a bastard (long story). And then she drops off the face of the Earth, never to be seen again.
 * An example that was caused by editing away a not-so-superfluous scene: Macross: Clash of the Bionoids was an American VHS release of Cho-jiku- Yo-sai Macross: Ai, Oboete Imasu Ka? with an English dub and over 20 minutes of running time cut. One of the cut scenes was that of Hikaru contacting the bridge of the Macross after the explosion of Boddole Zer's ship, leading to a case of "What Happened to the Main Character?"!
 * Bleach
 * In one episode a soul is sent to Hell, and it is explained why. Does it ever happen again, or even come up? Nope.
 * was left for dead. Did he die or live? Who knows. He hasn't been mentioned since.
 * Kensei fights Wonderweiss, rescuing Mashiro from him. He uses his Bankai, causing an explosion and then.... they disappear. After the battle, neither of them are shown with the recovering Visoreds, but aren't mentioned to have been killed either.
 * Nel completely vanishes after her fight with Nnoitra fails. The last time we see her, she is shown unconscious sitting against a rock, regaining consciousness just long enough to witness Nnoitra's death at the hands of Kenpachi and then she disappears again. Even worse is Dondochakka and Pesche, who after Szayel Apporo is defeated by Mayuri, are literally thrown into the fucking sky and are never seen or mentioned again. Kubo does mention them in volume omakes but leaves their status open-ended (the omakes are "is this a dream" type skits).
 * Ashido might be this manga's only genuine example of this trope. Kubo created the character and fully intended to use him but ran out of time to insert him into the manga. The anime decided to create a filler arc based around him and insert him where Kubo had originally intended to use him. However, the filler arc ended with him facing down the enemy to give the group time to escape and Rukia vowing to go back to Hueco Mundo to search for him. Did he live or die? Will Rukia ever go back for him? More importantly, will Kubo ever find the time to insert him into the manga like he wanted to or will Ashido forever remain unresolved filler? The truth is, we simply don't know.
 * In the first few seconds of Sonic X, there is a very short clip of a glowing silver hedgehog looking at the camera quite smugly, implying he is some kind of villain. Absolutely no mention or reappearance of said character occurs throughout the entire running of the show. Fans who picked up on an official screenshot and read its properties took to calling him "Nazo". One guy on Newgrounds even made his own anime one-shot about him (which he later re-made into a full-length three-parter, named "The Power of Nazo") which blatantly takes a huge amount of Dragonball Z influence. Alvin-Earthworm has said it is one of his favorite flash movies.
 * Vision of Escaflowne: Allen's owl and Dryden's mermaid.
 * More than that, what the hell happened to
 * Played with in Monster, when we're left wondering what happened to Tenma's date for a good third of the show.
 * To Aru Majutsu no Index was making plot threads in the last episode of the season. And the spinoff is apparently based in the same time period as the original, not a sequel that happens to have a new protagonist.
 * This is resolved by the simple realisation that Index is the anime adaption of the light novel series. Which has over twenty volumes, and is only implied to be nearing a conclusion because . The anime only reached volume 6. There IS now a sequel.
 * To Aru Kagaku no Railgun overlaps with Index's plot somewhat, but it's never outright mentioned in the series that it actually starts before the events of Index. The only thing that hints towards this is
 * An event with Mikoto and  is supposed to occur, which then involves her finding out about the rest of them, which immediately follows into the appropriate episodes of To Aru Majutsu no Index. Railgun has not reached this point, so it's quite a while behind Index.
 * In Pluto, Adolph Haas and his family vanish after partially answering a question about the past of main character Gesicht. This is despite the fact that Haas was a member of a Ku Klux Klan-esque anti-robot organization which is still presumably trying to kill him for messing up their plans with his own vendetta against Gesicht. It's particularly odd since Naoki Urasawa is usually pretty good about not leaving characters' fates hanging like this.
 * Admittedly Haas and his family aren't given a proper resolution. But his relationship with Gesicht had been resolved so it's not a total vanishment. However anti-robot organization does remain unresolved.
 * Mahou Sensei Negima:
 * One of the earliest examples appeared to be that claimed to be a martian from the future, and attempted to break The Masquerade in order to prevent a future tragedy. After she's defeated, she returns to her own time, and the whole "future tragedy" thing wasn't mentioned again.
 * There was also another one in the form of Zazie's appearance in the middle of this splash page in chapter 1, in which she has claws. This is never commented on or mentioned in any way in the story itself, leading to all sorts of fan theories and the eventual assumption that the author forgot about it. : She's
 * The whereabouts and activities of remain unclear, even though he survived his battle with Negi and promised that they would meet again. He suggested that he may know how to reverse the petrification cast on the inhabitants of Negi's village when he attacked it some time before the main story begins, but  and he vanishes completely
 * Negi's mother, Queen Arika, despite being incredible important and surviving the events that destroyed her country, is never mentioned again. Her reasons for abandoning Negi, or her inability to help, for the less cynical, are never revealed. Similarly, the significance of Negi being her heir and what he does about it is never touched upon.
 * During the, no mention is ever made of Anya or her fate. Interesting, as almost every other character is addressed, albeit sometimes indirectly.
 * In One Piece Straw Hat crew spend a while looking for a South Bird, and animal that always faces south, to take the Knock-Up Stream up into Skypeia. After they found one and got to Skypeia, it got away, but then came back and Chopper said it didn't want to stay in Skypeia (so it probably returned because it wanted help getting out). But then it's never seen again.
 * In the anime, during the G-8 filler arc it briefly attacks Vice Admiral Jonathan and then flies off. So I guess it just flew off and maybe stuck around somewhere in Navarone.
 * In the "From the Decks of the World" cover-story, the South Bird is shown to have returned to Jaya and mated with a North Bird.
 * Kizaru's role in the Fishman Island arc is this. He's first seen shortly commenting on the Fishman Pirates. One chapter later, he is seen capturing Arlong. Here, he gets an introduction box which in One Piece usually means that the character is going to play a somewhat important role. However, when Arlong is cross-examined by the Marines in the next chapter, there is no sign of Kizaru and he doesn't appear for the rest of the flashback. Sort of Justified in that Kizaru has had plenty of screentime and importance in the recent story as a whole, so only his role in the flashback exemplifies this trope.
 * Gin has never been seen again after the Baratie arc, and it is never explicitly stated whether he died from Krieg's poison.
 * Game X Rush has this whole set-up about Yuuki's past, particularly concerning his past as an assassin and how he acquired his assorted skills... which are later all but forgotten about completely, and no mention made of them again.
 * In general, Death Note manages to resolve most of its plot lines, and most events that occur early on have some sort of bearing on future events. That is except for arc in Volume II.  serves as only a minor detail in L's investigation  and is never mentioned again throughout the entire series. Of course, we know what happened, but the investigation team seems to lose interest pretty quickly (which is probably natural, given how well it's been covered up). Still, it's one plot point that, all told, has little relevance to the whole.
 * That, and at the end of the series,, but Word of God confirmed that.
 * The manga's ending appears to have a cult worshiping Kira. The leader of it looks like Misa.
 * Word of God says the girl in the manga's ending isn't Misa.
 * In Fairy Tail, near the end of the "Lullaby" arc, Natsu has a fight with "Grim Reaper" Erigor, the head of the Dark Guild Eisenwald. Natsu wins, but during a moment of distraction, Erigor goes missing. The characters even ask where he is, until more pressing concerns distract them again. We still have no idea where the heck Erigor is, and there doesn't seem to be any indication that Erigor will be mentioned again. Of course, Mashima-sensei has a talent for remembering little details and characters he's used in the past, and bringing them back later... but usually there's some evidence that he hasn't forgotten, even if it's just an Easter Egg. Erigor has literally never been mentioned again.
 * Erigor makes a brief reappearance in the anime during the early part of the Nirvana arc. For a rematch with Natsu. He gets CRUSHED in the span of about 3 minutes.
 * Also Angelica, that massive rat that Sherry kept with her on Galuna island. Sherry cried when it got hurt, and it was clearly alive at the end of the arc. The Nirvana arc, which couldn't have possibly happened more than a (in story) month later has her return, but the giant rat is gone.
 * Natsu has the nickname "Salamander" (due to his magic), and in the start of the series every mage outside of Fairy Tail calls him that. After the Tower of Heaven arc, the only one calling him Salamander is Gajeel, and other mages like the ones of Oración Seis and Grimoire Heart seem to have forgot the nickname. After the Edolas arc, even Gajeel seems to stop using the nickname, and Natsu loses his nickname for no apparent reason.
 * Tales From Earthsea has plenty, being an adaptation of several books at once. At the very beginning of the movie, Arren stabs his own father and takes his sword. While the sword becomes a plot point, the exact reason why he stabbed his father is not explained apart from some sort of "desperate rage". While Arren's fear of death (or rather, his life's insignificance due to everyone dying some day) leads to him becoming kind of crazy and suicidal at times, it does not explain the murder. Also in the opening scene, sorcerers are shown to lose their power and dragons fight in the sky. The king, before being killed, is informed of some sort of plague spreading and ill omens of "dragons returning from the West". Sparrowhawk is seen losing his powers as well, and says it's due to "the Balance being upset". The Balance is briefly mentioned to be between earth and sea, fire and wind (the dragon's established element), life and death. None if this is mentioned again. The plague is never explained, sorcerers are not shown to regain their powers even after the Big Bad is killed, and the dragons don't appear apart from one main character briefly turning into one at the climax.
 * In Bakuman｡, after, their assistants are out of work. One of them gets serialized around this time, and another finds work as his assistant. The third one has a wife and children, which is explicitly pointed out as a reason why this is quite bad for him, but we never find out what he does.
 * Presumably, he drops out and got a mundane job, just like Nakai vanishes after he quit the business.
 * Nope. He returns later on.
 * In Mobile Suit Zeta Gundam minor antagonist Gates Capa completely disappears after  without being given an on-screen death himself. Though this is shown to have some kind of mental effect on him, he never appears again in the series. It's a common belief that he was meant to appear in the sequel Mobile Suit Gundam ZZ at some point. In the Zeta novels, the
 * Initial D usually does a fairly good job of at least kinda giving closure to most of its minor characters (or reviving them for future arcs, a la Kai Kogashiwa), but there are two notable instances where Shuichi Shigeno was just plain brutal. First was Sayuki. After Takumi Fujiwara's duel with Impact Blue, they're seen at a water park, and it's strongly hinted that she has feelings for him. We'll never know for sure, unfortunately, because this is the last we ever see or hear of her. Second was the Night Kids. It's strongly hinted that they were a well-respected team before the Red Suns and Takumi came along to make a mess of things, and there are very palpable rumblings of dissention from Shingo Shoji. We see Takeshi Nakazato, once a dominant racer, lose to Seiji Iwaki, marking his third straight loss and second straight on his home turf. Seiji proceeds to publicly humiliate the team. And THAT'S IT; we never hear anything about Takeshi, Shingo, or the Night Kids ever again. (Oh yeah, Seiji also disappears into the mists a few chapters later.)
 * A rather literal semi-example of the trope: in Zipang a minor background character apparently considers a mouse living in temporary barracks as his pet, and is concerned when it doesn't show itself, which is a prelude to an artillery strike about to commence on the base. Several episodes later he is seen walking among survivors, holding a mouse, but no comment is made about him or the mouse.
 * The Puella Magi Madoka Magica Spin-Off Puella Magi Oriko Magica has a big one:  No answer is given.
 * The Absol Hunter J captured in her introductory episode in Pokémon for some reason was actually not reverted back from its statue form at the end of said episode unlike Pikachu, Meowth, and Gardevoir.
 * The well-dressed man who trades Ash for his Butterfree on the S.S. Anne seemed to be left for dead. The last we see of him he's standing by the trade machine after trading Butterfree back to Ash while Ash runs after Butterfree's ball, which slipped from his hands. Not long after that the ship capsizes. Considering we don't really know where the trade machine was on the ship, he may or may not have had time to escape. It's possible there's a well-dressed corpse somewhere in that ship.
 * Seitokai Yakuindomo pulls a silly version of this one in episode nine. Tsuda writes an essay for the school newspaper. Shino reads the first part of an sad story about a stray cat and is moved to tears. Arai takes over from that point and somehow gets to a point whether the cat is somehow floating out at sea in a storm and a sailor dramatically jumps overboard to save it saying "I'll leave the rest to you" to his crew; Aria is also moved to tears and Tsuda points out that nothing in that last scene had anything to do with what he wrote. Suzu is moved to tears finishing off the story starting from where Shino left off, but Tsuda demands to know what happened to George.
 * The Absol Hunter J captured in her introductory episode in Pokémon for some reason was actually not reverted back from its statue form at the end of said episode unlike Pikachu, Meowth, and Gardevoir.
 * The well-dressed man who trades Ash for his Butterfree on the S.S. Anne seemed to be left for dead. The last we see of him he's standing by the trade machine after trading Butterfree back to Ash while Ash runs after Butterfree's ball, which slipped from his hands. Not long after that the ship capsizes. Considering we don't really know where the trade machine was on the ship, he may or may not have had time to escape. It's possible there's a well-dressed corpse somewhere in that ship.
 * Seitokai Yakuindomo pulls a silly version of this one in episode nine. Tsuda writes an essay for the school newspaper. Shino reads the first part of an sad story about a stray cat and is moved to tears. Arai takes over from that point and somehow gets to a point whether the cat is somehow floating out at sea in a storm and a sailor dramatically jumps overboard to save it saying "I'll leave the rest to you" to his crew; Aria is also moved to tears and Tsuda points out that nothing in that last scene had anything to do with what he wrote. Suzu is moved to tears finishing off the story starting from where Shino left off, but Tsuda demands to know what happened to George.

Tsuda: "Yeah" my ass!"


 * In King of Thorn, Alice's rabbit is last seen wandering about holding her scrunchies, then later watching ... And then is never seen again after that. What happened to him? Was he destroyed in  impact? Was he unable to sustain himself for long, due to ? Is he hiding? Who knows!
 * In the Inuyasha manga, Kouga leaves before the final battle after getting both of the jewel shards permanently removed from his legs. He might have just gone home and stayed there, but unlike the rest of the characters, he never does get a definitive ending. He just disappears, and none of the other characters seem to really care what happened to him. Unless you count the anime, in which he.
 * YMMV. Kouga might be too major a character to be relevant for this trope. The manga also made it clear that his priority lay with the living members of his tribe who were suffering heavy losses because he was racing around trying to avenge the dead. Takahashi gave him a power-up arc to get him a tribal-specific weapon designed for protecting his tribe, emphasised how his lack of leadership was hurting his tribe and then wrote him out. YMMV as to whether Kouga was left hanging or very clearly had his storyline wrapped up.
 * Full Metal Panic! has Sarah Miller (Known as Kudan Mira in the original japanese.) People who have watched the entire series may be wondering, who the hell is Sarah Miller? Well, she's the red haired girl who is rescued by Sousuke in the very first episode. Her being kidnapped by Gauron (along with her unique hair color) imply that she is a whispered and therefore fairly important, but she is never seen again or even mentioned outside of that opening scene.
 * Mobile Suit Gundam 00: During the first season, the politicians of the major power blocs played an important if supporting roles. But by season 2, there's no mention of them after the time skip. The Union President does make a cameo at the season finale.
 * The same thing occurs to Celestial Being's Observers, who apparently monitor the organization in one episode. They're never seen or mentioned again in the show.