History ChekhovsGun / AnimeAndManga

** Edo Tensei was used by Orochimaru to resurrect the First and Second Hokage during the Invasion of Konoha Arc. It doesn't show up again for over 300 chapters until the Fourth Ninja World War arc, when Orochimaru's former BattleButler Kabuto uses it on [[UpToEleven an enormous scale]].

* Remember that absolutely unremarkable ruby used as an example by Antarcticite in ''Manga/HousekiNoKuni''? It'll be later used to awaken Padparadscha.

* In the ''Manga/FairyTail'' anime, [[spoiler:the sign that Laxus taught his grandfather has spread throughout the entire guild, as seen in Episode 2]].
** In [[http://www.mangareader.net/135-56905-1/fairy-tail/chapter-197.html the cover page]] for Chapter 197, "Bye Bye Fairy Tail", look at who's missing.
** [[spoiler:Gildarts' beating of Natsu and telling him that fear isn't evil and is sometimes necessary]].
** [[spoiler:Mystogan]] never formally quits being a member. He just stays behind at the end of the Edolas arc.
** The Dragon King Festival, mentioned in Chapter 100 and again in 292.

** ''Manga/DiamondIsUnbreakable'': Rohan and Koichi wander into a section of town connected to the afterlife. One of the rules of this area is that when you enter or exit, you cannot look behind you or your soul will be taken away. After leaving that part of town, this fact is quickly forgotten about until [[spoiler:the Stand, Cheap Trick, attaches itself to Rohan's back. Just as it's about to kill him, Rohan points out where he's led them to.]] And later on, [[spoiler:this is also how Reimi gets rid of Yoshikage Kira by having him forced to look behind the alley as he gets DraggedOffToHell.]]

** In Chapter 42, [[HopelessWithTech Kaguya]] sets up a Website/{{Twitter}} account so she can follow Shirogane and find out what he's doing over the summer, but is unable to work up the courage to send a follow request to his private account. [[spoiler:2 chapters later, she ends up using it as a cry for help when she's forbidden from attending the fireworks viewing with the rest of the Student Council.]]

** The Sports Festival arc establishes that the Student Council compiled a top secret file about the circumstances behind Ishigami's suspension in middle school. It's latter revealed that while the Student Council agreed to keep it secret on Ishigami's request, Fujiwara, frustrated since [[spoiler: the information would exonerate Ishigami]], kept the file in an open place in the Student Council room, in hopes that one day someone would stumble upon it. [[spoiler: That someone ends up being Osaragi, who passes on the information to Tsubame]]

* Roughly a third of the way into ''Manga/JoJosBizarreAdventureDiamondIsUnbreakable'', Rohan and Koichi wander into a section of town connected to the afterlife. One of the rules of this area is that when you enter or exit, you cannot look behind you or your soul will be taken away. After leaving that part of town, this fact is quickly forgotten about until [[spoiler:the Stand Cheap Trick attaches itself to Rohan's back. Just as it's about to kill him, Rohan points out where he's lead them to...]]
** This is also how [[spoiler: Reimi gets rid of Yoshikage Kira before ascending to heaven.]]
** The first episode of ''Anime/JojosBizarreAdventure'' shows [[spoiler:a carriage crash with Dario Brando and his wife trying to rob it. Dario opens a case and reveals an odd stone mask, which later on serves as the symbol for Part 1, and comes up again in Part 2.]]

* In ''Manga/BlackBird'', Kensuke gives [[spoiler:Misao]] a bottle of Whitesnake poison. This comes in handy when [[spoiler: she's trapped alone with Soujou.]]

* In the first episode of ''[[VideoGame/SuperRobotWarsOriginalGeneration Super Robot Wars OG: The Inspector]]'', [[VideoGame/SuperRobotWarsAdvance Axel]] has Soulgain unload a [[RocketPunch Genbu Goudan]] into Beowulf's Gespenst Mk. III's chest right before jumping to the main SRWOG-verse. In the finale, [[spoiler:when Beowulf has returned and become the show's final antagonist, [[VideoGame/SuperRobotWarsCompact2 Kyosuke]]'s trying to finish him off only to find his Alteisen Riese is out of ammo. Then he spots Soulgain's arm, still lodged in the Mk. III's chest. Cue Kyosuke using his Revolving Bunker to ram the fist into Beowulf's cockpit, finishing him off for good]].

* In the first episode of ''[[VideoGame/SuperRobotWarsOriginalGeneration Super Robot Wars OG: The Inspector]]'', [[VideoGame/SuperRobotWarsAdvance Axel]] has Soulgain unload a [[RocketPunch Genbu Goudan]] into Beowulf's Gespenst Mk. III's chest right before jumping to the main SRWOG-verse. In the finale, [[spoiler:when Beowulf has returned and become the show's final antagonist, [[VideoGame/SuperRobotWarsCompact2 Kyosuke]]'s trying to finish him off only to find his Alteisen Riese is out of ammo. Then he spots Soulgain's arm, still lodged in the Mk. III's chest. Cue Kyosuke using his Revolving Bunker to shove the fist into Beowulf's cockpit, finishing him off for good]].

* ''Manga/DetectiveConan'': It's frequently used and a regular watcher ends up being trained to look for them in every episode. They're particularly subtle, too. One episode involved the culprit wearing a headband with the name of her favorite singer. The singer, Okino Yoko, has an accent over the third 'o'[[labelnote:language note]]This is also the spelling as used in Wiki/TheOtherWiki. Elsewhere it is just written as ''ou''.[[/labelnote]]. When the culprit committed the crime, blood, which was the same color as headband, got on it (conveniently right on the accent mark), and was discovered by Mouri *cough* Conan *cough* as the killer. If you are an American viewer, you might tilt your head at the odd spelling at first since, hey! You don't know how Japanese worth squat! It was probably caught easier by Japanese viewers, but still subtle, and no one really pays attention to it until Conan provides the proof.

* ''Anime/{{Pokemon}}'':

** The anime gets away with this a few times too, the most prominent being in "Pika and Goliath" -- Ash revealed he kept the Thunderstone he got all the way back in "Electric Shock Showdown" in case Pikachu changed its mind about evolving. Though that was more of a RecycledScript in all honesty.

* Remember that absolutely unremarkable Ruby used as an example by Antarcticite in ''Manga/HousekiNoKuni''? It'll be later be used to awaken Padparadscha.

* In ''Manga/{{Monster}}'' a hospital director helps himself to the unconscious antagonist's candy. Nothing happens for a while. And then they find his body next to a candy wrapper.

* In episode 14 of ''LightNovel/FateZero'', Tokiomi mentions a treasure of Gilgamesh's he calls the "[[NamesToRunAwayFromReallyFast Sword of Rupture]]" which Gilgamesh is completely unwilling to use even though it could apparently easily destroy Caster's giant monster. In Episode 23 [[spoiler:Gilgamesh summons it during his fight with Rider and completely destroys his Reality Marble and his entire army with only a few seconds of charging.]]
* In the end of the ''Manga/{{Trigun}}'' anime, where [[spoiler: Vash brings the Crossgun with him to the final fight, and leaves it rooted in the ground. He later interrupts Knives by lifting it from the sand created in their fight and shooting him up.]]
* In the very first pages of ''Manga/RikiOh'', two guards chatter about how the eponymous protagonist has survived being shot five times in the chest when he sets off a metal detector. Forty chapters later, [[spoiler:the BigBad of the current story arc shoots him with a sixth bullet which completes the "GNOSIS" hexagram, a seal that strips him of all his power.]]
* In season 2 of ''Manga/NatsumesBookOfFriends'', our titular hero finds an ayakashi in his house, but he doesn't get rid of it because he finds out that it's harmless and can even prevent disasters from happening. [[spoiler: To stop the tragedy, it must sacrifice itself. It did just that and saved Natsume from an evil ayakashi in the process.]] At the very end of the episode, he collects the [[spoiler: remains of the small ayakashi]] saying that they're very precious to him.
* In the ''Webcomic/HetaliaAxisPowers'' [[TheMovie movie]], In the beginning of the movie, Italy is seen scribbling funny faces on the photos of TheFaceless [[AlienInvasion aliens]]. It turns out to be the key to defeating them.
* ''Manga/DoushitemoFuretakunai'': After being soclded for smoking at the office one too many times, Togawa finally decides that he should quit, and in order to do so, gives Shima a pack he just bought with the kanji for "forbidden" written on it, asking Shima to keep it away from him. [[spoiler:A month after their break up, Shima finds the pack while looking through his desk and breaks down crying, prompting an important talk with Onoda and deciding to make up with Togawa.]]
* ''Manga/OuranHighSchoolHostClub'' [[LampshadeHanging hangs a lampshade]] on this. The device that sets up the plot of the whole series is a large, expensive vase that will be broken. The vase is seen in the foreground of most of the shots leading up to the breakage...and is indicated by a large, blinking arrow. The blinking arrow returns in later episodes to point in every device and person whom will set the plot of the episode.

* ''Manga/{{Naruto}}'':
** The First Hokage's necklace that Tsunade gives Naruto becomes very important after the timeskip, as it becomes an essential instrument to control his Kyuubi powers.
** When Sasuke's Team Taka is fighting Killer Bee, there's a rather prolonged focus on a tentacle of the Eight Tails that Sasuke had cut off. It later turned out that Killer Bee hid inside it while being underwater, while transforming another tentacle to look like his unconscious body, deceiving Sasuke into thinking that he had captured Killer Bee.
** Itachi stuffed a crow down Naruto's throat, which comes out about 150 chapters later, and is revealed to be [[spoiler: one of Shisui's Sharingan eye.]]
** The cool space-time ninjutsu that Kakashi used in the Kazekage Rescue arc, appears again when [[BigBad Tobi]] is revealed to have the same ability, which also [[{{Foreshadowing}} serves as a clue]] to his [[TheReveal true identity]].
** The tablet hidden in the Naka Shrine is only readable with a Sharingan, and contains the reason for Uchiha Clan's creation (controlling the nine-tailed fox). It is revealed later that with a Mangekyou Sharingan and a Rinnegan, the full tale of the Sage of Six Paths and all the Tailed Beasts could be read from the tablet.
** Edo Tensei was used by Orochimaru to resurrect the First and Second Hokage during the Invasion of Konoha Arc. It doesn't show up again for over 300 chapters until the Fourth Ninja World War arc, when Orochimaru's former BattleButler Kabuto uses it on [[UpToEleven an enormous scale]].
** In the arc where Sai first appears, he refers to a dead brother. This is commented on quite a bit, showing Sai's lack of emotion and artistic ability. Much, much, much later, this turns out to be his BerserkButton, which is pressed by Kabuto in two ways.
* In ''Manga/RedRiver1995'', Prince Mattiwaza gives Yuuri one of his sister’s earring, which he always wears around his forehead as a keepsake, so that she can leave the Mitanni’s fortress without being held back by his soldiers. Yuuri wears that earring on her neck from then on, until the day she throws it toward Queen Nefertiti - Mattiwaza’s sister - to stop her from killing Ramses. The earring brings back Nefertiti’s memories of her brother and home country and holds her back for a while, which in turns saves Ramses’s life.
* Wendy Garret in ''Anime/GunXSword'' carries around a gun given to her by her brother, Michael, when their home was attacked. It only has one bullet. There may as well be a large tag on the handle saying "FUTURE PLOT DEVICE".
* In ''Franchise/YuGiOh'', if a character even explicitly obtains a given card (from a trade, a victory, or even just though picking it) rather than having it in their deck, it will be absolutely critical to their victory in at least one duel that season.
** In episode 139 of the [[Anime/YuGiOh first series]], Yami draws a card and places it on the field without looking at it, and Ishizu says that Yami knows the card is Fiend's Sanctuary. Yami's ability to predict and pull exactly the card he needs goes unnoticed until a hundred episodes later, when it's revealed how it exactly works.
** Shortly before Battle City, Yugi trades a card while out with Anzu for a Trap called [[http://yugioh.wikia.com/wiki/Lightforce_Sword Lightforce Sword]], which he later uses in the first duel of Battle City against the Exodia-using Rare Hunter and later against Strings, but after that, the card is not even mentioned again for ''thirty episodes'' when it plays a vital part of his duel against Kaiba in the finals of Battle City, saving him by delaying Kaiba from summoning [[PhysicalGod Obelisk the Tormentor]]
** Joey's Time Wizard! He's saved their necks with that card a ''lot''!
** The Deck Masters (Except for Joey's against the duel with Johnson) and some of the cards that Yugi and their friends (Specifically Serenity) during the Virtual World Arc.
*** Kuriboh actually helps save Yami Yugi from defeat, then, because of a card Rainbow Blessing, allows Yami Yugi to strike Gansley directly and win the duel.
*** The Dark Magician Girl helps Tea against by allowing her to summon Yugi's Dark Magician out of nowhere.
*** With Serenity, somebody who has never dueled before, she picks a card (St. Joan) thinking it looks cool. Combined that with her Deck Master's ability and with some help from Duke Devlin, her monster obliterates Nesbitt.
*** Kaiba's Lord of Dragon allowed him to summon a Blue Eyes White Dragon and obliterate Lector.
* In ''Anime/YuGiOh5Ds'', the final Signer Dragon, Life Stream Dragon, originally appeared in one of Luna's dreams. It was finally unlocked by Leo from Power Tool Dragon late in the series.
* In an episode ''Anime/YuGiOhZEXAL'', Yuma uses Baby Tiragon to beat Cathy three episodes after he got it from Tokunosuke as the token of their friendship.
** In the first episode, Yuma is looking over the cards he borrowed from his father's deck to try to find out what would be good to use in the duel against Shark, and is seen reading the effects of the card Double-Up Chance. He later uses that card in a combo with No. 39 to win the duel, and said card keeps being used in several more duels throughout the series. [[spoiler: It even helps him win his final duel of the series against Astral.]]
* Early in the second season of ''Anime/GhostInTheShellStandAloneComplex'' Togusa investigates the disappearance of a man who was last seen talking to people who have hired a number illegal immigrants as cheap laborers. It turns out he died in an accident while salvaging parts from an old nuclear power plant inside a restricted area. However, it's not a single episode about exploitation of refugees and [[NoOSHACompliance endangering workers]] [[CorruptCorporateExecutive to save money]], but kicks off the seasons main plot as [[spoiler:the BigBad initiated the illegal salvage operation to let plutonium fall into the hands of foreign terrorists to cause a massive scare against Chinese and Korean refugees]].
* In ''Manga/NegimaMagisterNegiMagi'', Ayase Yue's [[GreatBigBookOfEverything Orbis Sensualium Pictus]] and Saotome Haruna's [[SwissArmySuperpower Imperium Graphices]] were both created well before they became useful. Both Pactio artifacts were the main way for the [[TrueCompanions Ala Alba]] (not named that yet) to escape and defeat enemies during the arc. Nodoka's Diarium Ejus isn't as distant a creation to use timeline.
** A better example of a Chekhov's Gun in ''Negima'' is the bracelet that Ako won when she and Negi (disguised as Nagi) finished second in a pageant-like event during the school festival. Over a 150 chapters later, Ako is seen wearing the bracelet, with the item plying a key role in [[spoiler: stopping a Magia Erebea-corrupted Negi from attacking her and the rest of the Sports Girls.]]
** Spoileriffic example: Note Ku Fei's comment [[http://www.mangafox.com/manga/mahou_sensei_negima/v25/c229/12.html in panel five]], then read chapter 311.
** Way back in chapter 162, Chao brought her secret item, "Chao's family tree" that would indicate who will Negi marry in the future. It pops up again in chapter 349 (a copy of it at least) and this time, Negi's descendants are now a blank slate which means ''everyone'' gets a chance at being Negi's partner.
** The most shocking Chekov's Gun is [[spoiler:the truth about Poyo and Zazie Rainyday]]. For almost the entire manga, one of them is a background character with nothing interesting about them... [[spoiler:unless you noticed what Zazie looked like on the two-page spread in the very first chapter of the entire manga!]]
* ''Manga/MakenKi'':
** In chapter 11, Akaya asks Otohime why she was loitering on school grounds at Tenbi Academy. To which, she replies that she was investigating the validity of several rumors; including one that claimed even the dead could be [[{{Foreshadowing}} brought back to life]] there. It seems like a throwaway mention, until chapter 58, which is when Yuuka uses Makaru along with a Magatama stone to bring [[spoiler: Himegami]] BackFromTheDead.
** During Minerva's conversation with Himegami in chapter 12, Himegami's pupils briefly become slited like a dragon's. The reason is revealed during the flashback mini-arc between chapters 51-53, which reveals she's the biological daughter of Yatsuno, who was the [[spoiler: Yamato no {{Orochi}}]] in human form. Meaning, Himegami is half dragon.
** Yan-Min briefly alludes to combining Element when she explains to Aliliu and Lilu that [[CastingAShadow "Black"]] has the properties of the basic five Elements combined. She later uses the same knowledge in chapter 86, by combining her own "Blue" Element with Azuki's "Green" and Celia's "Red" to create [[LightEmUp "White"]]. Which is [[KryptoniteFactor the only thing that can hurt]] [[spoiler: Yamato Takeru and his clones]].
%%* ''Manga/AirGear'' has quite a few. See the series page for details.
* In the first part of the {{ecchi}} OVA ''Anime/LabyrinthOfFlames'', we briefly catch a glimpse of a Soviet T-34 tank during maintenance. Its reappearance towards the end of the second episode ([[ThemeMusicPowerUp powered up]] by ''[[UsefulNotes/RussianRelaxing Kalinka]]'', no less) doubles as the resident LovableSexManiac's SugarWiki/MomentOfAwesome.
* In ''[[Manhwa/ShinAngyoOnshi Blade of the Phantom Master]]'', the main character attacks a gun dealer about half-way through the movie after he is shown a little gun designed for hiding in a sleeve, which he keeps after he tosses the gun dealer into the sea. Guess what the penultimate blow to the bad guy uses.
* ''Manga/PokemonAdventures'' gets away with this more often than is healthy for the reader's mind. Lt. Surge's gloves, the feathers on Yellow's hat, a shard of the Grand Meteor (multiple times), and the list goes on. Almost every object explicitly discussed in dialogue returns later in the saga -- or even in a completely separate saga -- to turn the plot around.
* ''Anime/{{Pokemon}}'':
** The anime gets away with this a few times too, the most prominent being in "Pika and Goliath" -- Ash revealed he kept the Thunderstone he got all the way back in "Electric Shock Showdown" in case Pikachu changed its mind about evolving. Though that was more of a RecycledScript in all honesty.
** Ash won a King's Rock in a Pokémon sumo tournament in the Johto region and it was quickly forgotten. Fifty-three episodes later, Misty's Poliwhirl pulled the King's Rock out of Ash's backpack and it triggered its evolution into Politoed.
** In the well-known deleted scene to the first movie, known as "[[Radio/PokemonTheBirthOfMewtwo The Birth of Mewtwo]]", we've got a serious ChekhovsGun. Amber reveals that Pokémon tears are full of life, and though it seems unimportant at the time, it becomes very significant when [[spoiler: Ash is revived by Pokémon tears.]] "The Birth of Mewtwo" was cut from the English version, making [[spoiler: Ash's revival]] completely ridiculous...
---> My daddy used to tell me a bedtime story that when Pokémon are sad, and they cry...their tears are filled with life.
*** Actually, even the dub includes a very subtle ChekhovsGun for [[spoiler:Ash's revival]]: When Officer Jenny explains the boat trip to New Island was cancelled due to the storm, the woman accompanying her addressed that cave paintings explained that several Pokémon died in a storm, and that the survivors' tears revived them.
*** In the same movie, when Brock sees the missing Nurse Joy poster, after remarking that she's cute, he realizes that he recognizes her. It's later revealed that she was in fact the one who summoned them to New Island in the first place, under Mewtwo's MindControl.
* Two in ''Anime/PokemonOrigins'': the Pokémon Mansion (which contained information on Mewtwo), and the stones given to Red by Mr. Fuji (which allow Charizard to [[SuperMode Mega Evolve]]).
* In ''Manga/TsubasaReservoirChronicle'', the eponymous reservoir, while it appears halfway through the story, does not seem relevant until the final arc, where a flashback and a [[TheReveal reveal]] make it retroactively the most important location in quite possibly the entire CLAMP multiverse. Shoulda known Creator/{{CLAMP}} wasn't just throwing in random words.
* ''Anime/{{Gankutsuou}}'' has many. One is a gun placed in a desk drawer by Fernand. The two suits of armor outside the Morcerf mansion are actually giant mecha. Then there's the watch given to Albert by The Count when they first met.
* Stock in trade for ''Manga/EatMan'', where Bolt Crank may spend the entire adventure snacking on a bag full of bolts and other small machine parts. At the climax however, he'll swallow the last bolt, then whip a {{BFG}} he'd just finished eating the last of.
** Really, if he eats something at any point in the story, you can expect him to use it later, even if he obviously didn't plan to. For example, in one chapter, he escapes from being locked in a safe by eating the safe. Later, [[spoiler: He's caught in a massive explosion... and survives by hiding in the safe]].
** There's also a subversion, during the MOLE arc. Early on, Macus is playing with a yo-yo and musing on how, in Zero-G, the yo-yo goes all the way to the end of its string regardless of what direction it's thrown. Bolt promptly eats it. [[spoiler: Later, Macus has his legs cut off by lasers and is set adrift. Bolt whips out the yo-yo and sends it in his direction... But the string isn't long enough to reach him]].
* ''VisualNovel/{{Clannad}}'': Remember those orbs of light Miyazawa and the Girl in the Illusionary World were talking about? Those'll really come in handy [[GainaxEnding much]] [[GrandFinale later]].
* A few times in ''Manga/RanmaOneHalf'': the horned mongoose whistle [[EasyAmnesia Shinnosuke]] gave Akane ten years ago turns out to be the key to pacifying and sealing the {{Orochi}} of [[MisplacedWildlife Ryugenzawa]]. The photo of Akane that Nabiki snapped (and tried to sell to Ranma, but was bought by Ryouga) gave him the impetus to save himself from a rockslide, and was later used by the bad guys to kidnap her.
* In ''Anime/MacrossFrontier'', [[IdolSinger Sheryl]] loses one of her earrings ([[CallBack inherited from her mother]]) when Alto crashes into her in mid-performance. She goes nuts looking for it, but later tells him to keep it as a good luck charm during combat (at which point it's lost forever.) It is later revealed that the earrings are made of [[spoiler:[[AppliedPhlebotinum Fold Quartz]], a material that can transmit thoughts and emotions across the galaxy, and she (and Alto) use the remaining one during the GrandFinale to communicate with the [[BigCreepyCrawlies Vajra]]]]. It became so important, the Blu-Ray release of ''Anime/MacrossZero'' went back and [[{{Revision}} added the earrings]] [[CallForward in a scene with Sheryl's ancestors]].
** ''Macross Frontier'' gets points for sneaking ChekhovsGun into what looks to be a throw-away AccidentalPervert gag. [[spoiler:The fact that the Vajra start retreating from Island 1 just after Ranka's scream in that scene is no coincidence.]]
* In ''Anime/SailorMoon'', when Mako/Sailor Jupiter is introduced in the first season of the anime her rose-shaped earrings sparkle with reflected light. They seem insignificant until the beginning of the fifth season, when [[spoiler: Usagi is trapped in Queen Nehelenia's illusions and loses the will to press on to save Mamoru and Chibi-Usa. When Jupiter shields Usagi with her body to block Neheleni'a lightning attacks one of Jupiter's earrings falls off and Usagi finds it later; the rose shape reminds her of her love for Mamoru, and she jolts herself out of her illusion to continue to save Mamoru.]]
* ''Anime/EurekaSeven'' features a very sneaky ChekhovsGun in the form of Eureka and Anemone's collars. They seem like random accessories until the ''very last episode'', where it's revealed that they're [[spoiler:devices meant to destroy the Scub Coral, triggered by Dewey Novak's suicide.]]
** Kinda foreshadows its significance in episode 11 when Eureka does not take the collar off when bathing and episode 19 when the collar was intact while Eureka's clothes and hair were being consumed by the Scab Coral.
* In ''VideoGame/{{Utawarerumono}}'', Eruru wears an odd, apparently decorative loop in her hair at almost all times. Later it is revealed that [[spoiler:it is some sort of transmitter originally made by the humans when it automatically opens the door to a human research facility.]]

*** Ukitake was afflicted with a lung disease at a very young age that turned his hair white, but he was able to survive and even remain healthy enough to become a powerful Shinigami. [[spoiler:He survived because of a "God" called Mimihagi-sama, the Right Arm of the Soul King, which is connected to the Kamikake seen in chapter 605. He uses it to replace the Soul King after his demise.]]
* ''Franchise/LyricalNanoha'' has Chekhov's Wave Motion Gun; an early episode in ''A's'' gives us an apparently throw-away scene involving a high-powered magical cannon, the Arc-En-Ciel. The Arthra is out of service most of the season being refitted. When it returns, what should it come equipped with, but an Arc-En-Ciel.
** Oh please. There's another one which is WAAAAAAAAY back in season 1: Wide Area Search. Simple spell just to collect the magical jewel shards right? [[spoiler: During the final battle, Nanoha used this again to track down [[SmugSnake Quattro]].]]
** In conjunction with the above spoiler, Season 3 (''[[Anime/MagicalGirlLyricalNanohaStrikers StrikerS]]'') opens with Nanoha rescuing a girl from a raging fire and using Divine Buster to blow a hole clear through the entire building to get her out. That scene is ''nothing but Chekhov's Guns''. The girl becomes Subaru, whose origins are crucial to the plot and lead you to one of the big Wham Moments of the season; and Nanoha [[spoiler: stalls in a battle while doing Wide Area Search so she can stop Quattro, who when it is way too late remembers Nanoha has an attack that can also serve as the biggest DungeonBypass in history.]]
* In ''Manga/{{Monster}}'' a hospital director helps himself to the unconscious antagonist's candy. Nothing happens for a while. And then they find his body next to a candy wrapper.

* In the ''Manga/VampirePrincessMiyu'' TV series, Miyu and Chisato purchase two good-luck charms from [[ChekhovsGunman an artisan]]. [[spoiler: The artist is a Shinma, and the trinkets keep Miyu from sensing Chisato's own energy, as she is an exceedingly powerful Shinma who hasn't been awakened yet.]]
* ''Anime/LupinIII'':
** ''Anime/TheCastleOfCagliostro'', there are a few details you might miss the first few times you watch the movie:
*** Right before Lupin and Jigen are attacked in their room by the Count's assassins, you see Lupin fiddling around with some sort of forgery kit. What's he doing, you ask? [[spoiler: Making the fake ring he gives to the Count about halfway through the film.]]
** In ''Anime/TheMysteryOfMamo'', Goemon's sword is shattered in a duel and Lupin takes one of the shards. [[spoiler:In the climax of the movie, Lupin uses the shard to save himself by reflecting Mamo's lasers back at him.]]
* Griffith's Crimson Behelit in the ''Manga/{{Berserk}}'' anime. We first see it after the naked water fight that he and Guts have in an early episode, and apart from a different colored Behelit taken off a demon Guts kills in the very first episode, it doesn't have a lot of significance, save for Zodd's prophetic warning about how when Griffith's dream crumbles, Guts will face his death. The Crimson Behelit turns out to be [[spoiler:the key to become the very next member of the Godhand, the {{Big Bad}}s of the series, during the Eclipse, and when it activates, it's the point when [[FromBadToWorse everything goes straight to Hell]] for Guts and the Hawks that [[MoralEventHorizon Griffith led]].]]
* ''Anime/TransformersRobotsInDisguise'' had a particularly impressive example. When the Decepticons were introduced, Scourge's protoform scanned a truck that Kelly was trying to escape in, and which Optimus Prime was holding up, meaning he simultaneously scanned Prime. Initially, the only outcome of this seemed to be a Decepticon who was ironically similar in appearance to the Autobot leader. ''Much'' later, it turned out that this event had given Scourge a hybrid Predacon/Autobot/human spark based on that of Optimus Prime, which in turn allowed him to control Fortress Maximus.
* In ''VisualNovel/WindABreathOfHeart'', everybody has a special power. Except the protagonist. This point is made whenever the subject of the powers comes up, suggesting that the protagonist will eventually awaken to a kickass power. Oddly enough, the episode in which he uses his power was taken out of the TV broadcast.
* In ''Anime/{{Mazinkaiser}}'' episode six, Boss gives Kouji a bar to protect him while trying to get to Mazinkaiser. Kouji accepts it, but points out he has protection in the form of his Photon Gun. In the next (and final episode), Mazinkaiser's steering wheel is destroyed in battle with Hell King Gorgon. As the machine tumbles back, the bar tumbles out and Kouji remembers Boss giving it to him, causing him to shove it in the shaft and finish the fight.
** The sequel movie, ''Deathmatch! Great General of Darkness'' has an interesting one, though - way back in Mazinkaiser episode one, the titular mech thrashes an altered Mazinger-Z and it is never seen in the series again and it is never mentioned as to its fate. Come the movie, a knife Kouji uses to defend himself is revealed to be made from Mazinger-Z's remains!

* ''LightNovel/ShakuganNoShana'' has a Chekhov's {{BFS}}, Blutsauger. It first appears in the hands of a minor antagonist, and when he's defeated, leaving the sword, any viewer could correctly deduce that by the end of the season, it will be in [[TheHero Yuji's]] hands. Although it trades hands several times, Yuji does indeed use it in the first season finale, and in the second half of the second season he carries it regularly.
** There was also the antifire ring, which shows up with the first minor antagonist and is given to Yuji afterwards. He uses it to survive two later fights, including the finale of the first season.
* The tiny bombs that Sagara Sanosuke got from Tsukioka Tsunan in ''Manga/RurouniKenshin'' play an important role in the Kyoto Arc when Sagara uses them to blow up Shishio's battleship, earning a major victory for Kenshin and company.
* Miaka Yuki's unborn child in the 3rd ''Manga/FushigiYuugi'' OVA. The only Shinazho that wasn't a MacGuffin.

* ''Anime/ZoidsChaoticCentury'' has a pretty big one. Remember The Valley of The Rareherts? It turns out that [[spoiler: Zoid Eve is located in there.]]
* Where to ''begin'' with ''Anime/MyHime''? Seriously, this series has ''great'' rewatch value.
** [[spoiler:Mikoto's penchant for [[BigEater passing out from hunger]]:]] First shown in Episode 2, SugarWiki/{{Funny Moment|s}} in Finale.
** [[spoiler:Shizuru's [[PsychoLesbian thing]] for Natsuki:]] my Mom, ''somehow'', picked up on it in their ''first onscreen interaction, the first time she watched the series'' in Episode 3, becomes important in Episode 21.
** [[spoiler:[[YaoiFangirl Aoi and Yayoi's]] fantasy]] in Episode 5. See Episode 17. Because they were right about ''everything''. [[spoiler: Except for [[SweetPollyOliver Akira's gender]].]]
** [[spoiler:The wedding kimono:]] Makes its first appearance in Episode 6, becomes a ''vital'' clue for the audience in Episode 18.
* ''Anime/RevolutionaryGirlUtena'' is mostly just clever storytelling and repetition so it's actual {{ChekhovsGun}}s are much harder to spot. Akio's planetarian is one of them, but a much more significant one is the Sword of Dios, drawn from Anthy's bosom every other episode. No one asks why. Come the second arc onwards [[spoiler:swords are being drawn from everyone's chests]]. [[spoiler:And, to cap it off, then the Sword of Dios has to be drawn from Utena's breast.]]
* There's actually a fairly elaborate one in ''Anime/TanteiOperaMilkyHolmes'' at the end of season 1. Mary and Kate from episode 5 inspire Milky Homes to not give up. Aileen from episode 4 gives the girls transportation to their final battle, the recurring Pig-Faced character comes by to deliver a Toys-Powered Ring from Sonya (episode 9) and a wedding plate from Claris (episode 6), Sherlock's various encounters with [[DarkActionGirl Henriette's]] Cleavage also come into play as well.[[spoiler: The ring winds up saving Sheryl's life, the plate becomes crucial for Cordelia's defeat of [[MasterSwordsman Stone River]], and Sherlock's previous brushes with Henriette ACTUALLY become a way for Milky Holmes to identify her as [[PhantomThief Arsene]]. ]]
* The mangaka of ''Manga/SweetBlueFlowers'' and ''Manga/WanderingSon'' frequently includes characters that looks like they'll only appear once or twice, or that don't have much to them, that become important characters later on. Same thing with plot devices.
%%* [[http://mangafox.com/manga/rosario_vampire_11/v02/c006/22.html Chekhov's Breasts]]
%%* ''Anime/TheIdolMaster'' - Haruka's present for the Producer, a wallet.
* In ''Anime/SpiritedAway'', the gift that Chihiro received from [[spoiler: the river god]] was able to cure Haku from his injuries and free Noh Face from all the food (and people) he had eaten.
* In ''AudioPlay/SaintBeast'', an angel helping Shin move drops a stack of his books, and the first one Shin picks up is about witchcraft transformation. The MonsterOfTheWeek? An evil tree that's actually an angel who underwent witchcraft transformation. Overlaps with SomeDayThisWillComeInHandy.
* ''Anime/{{FLCL}}'' episode "Brittle Bullet". Ninamori receives a water pistol during the episode. At the end she uses it to cool off Naota after he's ejected from Conti.
* Early in ''Anime/PrincessMononoke'' Eboshi warns that a wolf's head still has the power to bite, even after being severed. Guess how she loses an arm later?
* Inverted in ''Manga/YokohamaKaidashiKikou'' -- the story introduces tons of "unnecessary elements," never using them. This includes characters that are introduced but never meet each other, offers that are never used, and an actual gun that is never seen again after its introduction.
* In the ''Anime/YesPrettyCure5'' movie, Urara is shown having just caught a Pinky and storing it in her TransformationTrinket. Come the end of the movie, when the BigBad uses the Dream Collet to grant his wish after gathering ''all'' of the Pinkys, he realizes it's not working - Urara then mentions that, whoops, [[SpannerInTheWorks she didn't put the one she caught in the Collet]], unintentionally foiling his plan.
* Yuuta's collection of items related to his "[[OldShame Dark Flame Master]]" in ''LightNovel/LoveChunibyoAndOtherDelusions'', which he originally planned on throwing away come tenth-grade, turn out to be useful whenever he has to distract and/or keep Rikka and friends occupied.
* ''Manga/XxxHolic'' has the egg given to Domeki by Yuuko, who tells him that it'll be useful somewhere down the road. [[spoiler: Subverted in that even though it's brought up regularly, the right time for it to be used never comes.]]
** In the first volume of the manga, Watanuki finds [[Manga/CardcaptorSakura Sakura's staff]] in the storeroom, and Yuko tells him it's just a plastic toy. [[spoiler: '''Nope.''' That's the real deal, and it's ''extremely'' important.]]

* In ''Manga/YuYuHakusho'', [[spoiler: Koenma's pacifier]] which is even referenced during the Dark Tournament Arc as being significant in an off-hand scene with Koenma and Ogre. [[spoiler: It turns out to be an artifact to create a nearly unbeatable barrier that Koenma tried using on Sensui.]]

** Kotetsu's nickname of "Bunny" tends to aggravate Barnaby to no ends. In episode 23, [[spoiler: Barnaby's memories return when Kotetsu uses it.]]
* At the beginning of the Monkey Hunter arc of ''Manga/{{Gintama}}'', Gintoki ends up getting his...joystick turned into a hexagon screwdriver, which ticks him off to no end, partly because of how rarely one would ever need such a screwdriver. Come the end of the arc when he confronts the aliens responsible for the deed, it turns out the only thing that can stop their ship's engine is precisely that. [[VulgarHumor The scene is about as awkward as one might imagine.]]
* [[ChekhovsArmoury There are a TON of these in]] ''Manga/BlackButler''. Most of them overlap with one of the subcategories of this trope, except for the pairings in chapter 71 of the manga, and several examples from the anime.

* ''Anime/AldnoahZero'' uses a literal example in episode fifteen, where Slaine is shown seemingly firing randomly into orbit hours before a battle. Later in the episode, he maneuvers an enemy right into the calculated path of the orbiting barrage as it swings around through the battlefield. Proving yet again that [[VideoGame/MassEffect2 "Sir Isaac Newton is the deadliest son-of-a-bitch in space"]].
* In ''Anime/GirlsUndPanzer,'' Mako is only willing to join the Tankery team to get amnesty for all the times she's been [[BrilliantButLazy late to school]]. At the end of Episode 12, [[spoiler: Sodoko gets Mako's attention and lets her see that all the tardies have been erased, leaving Mako with a clean record.]] Cue one [[OOCIsSeriousBusiness Glomp]] from Mako.
* ''Manga/AttackOnTitan'':
** A minor example: when Annie agrees to help Armin [[spoiler:to get Eren out of Stohess]] she conspicuously puts on a plain metal ring that no one has been seen with. It comes up later when [[spoiler:she's apprehended as the Female Titan and gagged to prevent her from shifting, she opens it up to reveal a hidden barb so she could pierce her finger that way]].
** When Armin makes his (panicked) initial analysis at the start of Trost, he quickly mentions that the humans have no way of moving the gigantic boulder that's large enough to block the entrance, much less actually repairing the gate before the Titans make it in. [[spoiler: Later on, Eren manages to move the boulder and seal the gate as a Titan.]]
* In the ''Manga/FairyTail'' anime, [[spoiler:the sign that Laxus taught his grandfather has spread throughout the entire guild, as seen in Episode 2]].
** In [[http://www.mangareader.net/135-56905-1/fairy-tail/chapter-197.html the cover page]] for Chapter 197, "Bye Bye Fairy Tail", look at who's missing.
** [[spoiler:Gildarts' beating of Natsu and telling him that fear isn't evil and is sometimes necessary]].
** [[spoiler:Mystogan]] never formally quits being a member. He just stays behind at the end of the Edolas arc.
** The Dragon King Festival, mentioned in Chapter 100 and again in 292.
* In volume one of ''Manga/AssassinationClassroom'', [[MasterPoisoner Okuda]]'s DayInTheLimelight chapter involves her giving Korosensei a concoction that turns him into a blobby form with even more speed than usual. Later, all the way in ''volume seventeen'', [[spoiler:the class discovers that said concoction reduces the likelihood of his anti-matter cells exploding to less than 1%, and might be the key to saving his life.]]
* ''Franchise/DragonBall'':
** One that crosses two series and twenty years. In ''Anime/DragonBallZ''[='s=] Cell Saga, Bulma, Gohan and Future Trunks discover another version of Trunks' time machine, which was later revealed to have been stolen by Cell when he killed his timeline's Trunks. Flash forward to ''Anime/DragonBallSuper''[='s=] Black Goku Saga [[spoiler:and it's revealed that Bulma ''kept'' the time machine and she pulls it out when Black Goku destroys' Trunks' time machine with the intent on stranding him in the past.]]
** Another example of the Future Trunks arc: Early on, Goku is given a button by [[TopGod Zen'o]] so that he can call him down whenever needed. Sure enough, in the final episode of the arc, [[spoiler: Goku uses the button to deal with Zamasu after he transforms into an EldritchAbomination.]]
** One change that ''Super'' made in its retelling of ''[[Anime/DragonBallZBattleOfGods Battle of Gods]]'' was to set it all on a cruise ship, rather than Bulma's backyard. Although mostly just a minor, somewhat random change, it comes into play in the GrandFinale, where [[spoiler: Bulma gives it to Android 17 as a reward for saving the universe in the Tournament of Power.]]
* In ''[[Anime/Danganronpa3TheEndOfHopesPeakHighSchool DanganRonpa 3 Side:Future]]'', we have Seiko's Cure-W. She first uses it to (unsuccessfully) try and stop Daisaku Bandai from dying to the bangle poison. It makes a few appearances through the rest of Side:Future, but doesn't really come into play until [[spoiler: Side:Hope]], where its' revealed that it ''actually works'', as [[spoiler: Kyoko Kirigiri]] can now testify.
* ''Franchise/{{Gundam}}'':
** In ''Anime/TurnAGundam'', the titular mobile suit is hidden inside a statue.
** A similar situation can be found for the Build Burning Gundam from ''Anime/GundamBuildFightersTry''. [[spoiler:It's [[PowerLimiter hidden inside a Dom.]]]]
* ''Manga/CityHunter'':
** When Hideyuki Makimura was killed by a victim of the Angel Dust, Ryo reacted badly to the mention of the drug, and was astonishingly well-informed on its effects and its makers of Union Teope in spite of them being newcomers in Japan (and him having never heard the name before Hideyuki mentioned it). Near the end of the story it's discovered that Ryo was the original test subject of Angel Dust, and the founder and leader of Union Teope was his adopted father.
** Ryo's backstory is hinted at in many places by Ryo, other characters who knows it and small happenings before Rosemary Moon decides to reveal it. Even then, she left out some parts that would be revealed only later.
** Not just Ryo's backstory, but also other parts of the story, sometimes mixed with Continuity Nods. For example, in his first appearance Silver Fox tried to kill Ryo's target with a rifle chambered for .308 Winchester, and at the start of his second appearance the first hint of him being the villain is the sight of a rifle usually chambered for that round.
* ''Manga/{{Claymore}}'' has a Chekhov's Gun that could have the longest duration and the biggest payoff: Clare became a Claymore by [[spoiler: implanting Teresa's flesh within her]]. During the final battle, Clare regains her HeroicSecondWind and Awakens perfectly... [[spoiler: in the form of Teresa]].
* In ''Anime/DarlingInTheFranxx'', Hiro's inability to pilot with anyone but Zero Two is revealed to be one. [[spoiler:Because Hiro licked the blood off her scraped knee as a child, he was afflicted with Zero Two's curse. His scores began to plummet afterwards, going from one of the most promising pilots to a complete washout. He was even labeled as a "tainted specimen" because of the incident.]]
* In ''LightNovel/SwordArtOnline'':
** During the "Mother's Rosary" arc, it's mentioned in passing early on that Asuna has a second ALO account with a Sylph character named Erika. Other characters suggest that Asuna use Erika to challenge Zekken (aka Yuuki), but Asuna decides not to, since she's more comfortable using her Undine healer. Asuna later has her mother log on to Erika when she shows her the house that she bought in ALO (another Chekhov's Gun in and of itself), which not only is like the one Asuna owned in SAO, but looks very much like her maternal grandparents' house.
** In the light novel version of the Alfheim arc, Kirito and Leafa take a brief detour through Jotunheim, catching a glimpse of the legendary sword Excalibur in the process. This ends up being a double example, because not only does Kirito summon the sword with his admin powers during the battle with Oberon, but the Calibur arc is about the quest to find the sword.
** In ''Alicization'', Cardinal mentions that the gods of the Underworld, while technically fake, do exist as super-accounts that the supervisors use in case of emergency. They end up being used during the War of the Underworld arc- Asuna uses Stacia, Leafa uses Terraria, Sinon uses Solus and [[ArcVillain Gabriel]] uses [[DarkIsEvil Vecta]].
* ''Anime/TomicaHyperRescueDriveHeadKidouKyuukyuuKeisatsu'' gives us Pit, the cute but easily forgotten RobotBuddy who's always running around. [[spoiler: Actually, Pit contains data of Gou's deceased grandfather Joutarou, who has been observing the drivers all along and provides vital help in taking down the Evil AI.]]
* In perhaps one of the oddest examples of Chekhov's gun, an early episode of the ''VideoGame/SenranKagura'' anime shows [[TooKinkyToTorture Ryōna]] is so "experienced" with rope that she can even tie herself up, bondage style. This is presented as just another gag of how perverted and masochistic she is. [[spoiler: But when a giant yōma proves to be impervious to attack, Ryōna busts out a giant rope and quickly ties it up.]]
* ''Manga/KaguyaSamaLoveIsWar'':
** In chapter 42, [[HopelessWithTech Kaguya]] sets up a Website/{{Twitter}} account so she can follow Shirogane and find out what he's doing over the summer, but is unable to work up the courage to send a follow request to his private account. [[spoiler:2 chapters later, she ends up using it as a cry for help when she's forbidden from attending the fireworks viewing with the rest of the Student Council.]]
** Chapter 60 establishes that one of the perks of being StudentCouncilPresident is a letter of recommendation allowing access to any university in the world. In Chapter 111, [[spoiler: Shirogane announces his intent to study abroad]]. And then Chapter 137 reveals that [[spoiler: because Shirogane was elected twice, he's allowed two letters of recommendation, and he wants to use one of them to let Kaguya get accepted into Stanford with him]].
** The Sports Festival arc establishes that the Student Council compiled a top secret file about the circumstances behind Ishigami's suspension in middle school. It's latter revealed that while the Student Council agreed to keep it secret on Ishigami's request, Fujiwara, frustrated since [[spoiler: the information would exonerate Ishigami]], kept the file in an open place in the Student Council room, in hopes that one day someone would stumble upon it. [[spoiler: That someone ends up being Osaragi, who passes on the information to Tsubame]]
* Remember the RobotGirl model with the inscription "Rei 01" that Senku sees in the first chapter of ''Manga/DrStoneRebootByakuya''? During the story's final chapter [[spoiler: it's shown that Rei remade itself in her image]].
* ''Manga/BlackClover'':
** The Third Eye use Trinity Sealing Magic to store incredibly large amounts of mana, which is first seen in Chapter 53. Licht releases this seal in Chapter 144, using the entirety of the mana to cast his Arrows of Judgement, raining down light blades on the entire Clover Kingdom and forcing Julius to sacrifice himself.
** Sally's human chambers are first seen in Chapter 37. In Chapter 182, they're used by Rhya to reincarnate Vetto and Fana a second time in artificial bodies.
** Yuno's pendant is part of a group of stones that can power up elves and, apparently, open magic seals. It is used specifically to open the seal of Zagred. The pendant is later revealed to be an heirloom of his biological family [[spoiler:the House of Grinberryall, the former rulers of the Spade Kingdom.]]
** Early on a spherical magic item is seen in Hage near the skeleton of the demon that the first Wizard King defeated. [[spoiler:It's later revealed to be an invention created by the first Wizard King and Secré. And Julius has been storing his Time Magic inside it, using it to revive himself as a 13 year old when he's fatally stabbed by Licht.]]
* In ''Manga/ExcelSaga'', Elgala finds a gold bar in Volume 11 that she hopes will help the trio with their finances. It goes missing for ''six volumes'' and turns up in Volume 17 [[spoiler:when the City Security troop find it going through their garbage and Kabapu is able to use it to build capital to regain access to hidden funds and resume his power base.]]
* In one scene in ''Anime/SonicTheHedgehogTheMovie'', Dr Eggman lets off a missile in the shape of a tortoise; it moves so slowly that it is of very little use to him in the fight. At the end of the film, after Eggman's clone of Sonic is destroyed, he announces that he still has Sonic's DNA and he can make another clone; at this point the tortoise re-enters shot and explodes, destroying the data disk.

* In ''Manga/AnatoliaStory'', Prince Mattiwaza gives Yuuri one of his sister’s earring, which he always wears around his forehead as a keepsake, so that she can leave the Mitanni’s fortress without being held back by his soldiers. Yuuri wears that earring on her neck from then on, until the day she throws it toward Queen Nefertiti - Mattiwaza’s sister - to stop her from killing Ramses. The earring brings back Nefertiti’s memories of her brother and home country and holds her back for a while, which in turns saves Ramses’s life.

%%* ''Anime/TheIdolmaster'' - Haruka's present for the Producer, a wallet.

* Roughly a third of the way into ''Manga/JoJosBizarreAdventure: Diamond is Unbreakable'', Rohan and Koichi wander into a section of town connected to the afterlife. One of the rules of this area is that when you enter or exit, you cannot look behind you or your soul will be taken away. After leaving that part of town, this fact is quickly forgotten about until [[spoiler:the Stand Cheap Trick attaches itself to Rohan's back. Just as it's about to kill him, Rohan points out where he's lead them to...]]

* In ''Manga/MahouSenseiNegima'', Ayase Yue's [[GreatBigBookOfEverything Orbis Sensualium Pictus]] and Saotome Haruna's [[SwissArmySuperpower Imperium Graphices]] were both created well before they became useful. Both Pactio artifacts were the main way for the [[TrueCompanions Ala Alba]] (not named that yet) to escape and defeat enemies during the arc. Nodoka's Diarium Ejus isn't as distant a creation to use timeline.

* ''Manga/MakenKi''

* In the first part of the {{ecchi}} OVA ''{{Labyrinth of Flames}}'', we briefly catch a glimpse of a Soviet T-34 tank during maintenance. Its reappearance towards the end of the second episode ([[ThemeMusicPowerUp powered up]] by ''[[UsefulNotes/RussianRelaxing Kalinka]]'', no less) doubles as the resident LovableSexManiac's SugarWiki/MomentOfAwesome.

* In ''Anime/{{Monster}}'' a hospital director helps himself to the unconscious antagonist's candy. Nothing happens for a while. And then they find his body next to a candy wrapper.

* Where to ''begin'' with ''Anime/MaiHime''? Seriously, this series has ''great'' rewatch value.

** [[spoiler:Shizuru's [[PsychoLesbian thing]] for Natsuki:]] my Mom, ''somehow'', picked up on it in their '' first onscreen interaction, the first time she watched the series'' in Episode 3, becomes important in Episode 21.

* There's actually a fairly elaborate one in ''Anime/TanteiOperaMilkyHolmes'' at the end of season 1. Mary and Kate from episode 5 inspire Milky Homes to not give up. Aileen from episode 4 gives the girls transportation to their final battle, the recurring Pig-Faced character comes by to deliver a Toys-Powered Ring from Sonya (episode 9) and a wedding plate from Claris (episode 6), Sherlock's various encounters with [[{{DarkActionGirl}} Henriette's]] Cleavage also come into play as well.[[spoiler: The ring winds up saving Sheryl's life, the plate becomes crucial for Cordelia's defeat of [[{{MasterSwordsman}} Stone River]], and Sherlock's previous brushes with Henriette ACTUALLY become a way for Milky Holmes to identify her as [[{{PhantomThief}} Arsene]]. ]]

* ''Franchise/DragonBall''

* In ''[[{{Anime/DanganRonpa3}} DanganRonpa 3 Side:Future]]'', we have Seiko's Cure-W. She first uses it to (unsuccessfully) try and stop Daisaku Bandai from dying to the bangle poison. It makes a few appearances through the rest of Side:Future, but doesn't really come into play until [[spoiler: Side:Hope]], where its' revealed that it ''actually works'', as [[spoiler: Kyoko Kirigiri]] can now testify.
* Franchise/{{Gundam}}:

** A similar situation can be found for the Build Burning Gundam from ''Anime/GundamBuildFightersTry''. [[spoiler:It's [[{{PowerLimiter}} hidden inside a Dom.]]]]

* In ''LightNovel/SwordArtOnline''

* In perhaps one of the oddest examples of Chekhov's gun, an early episode of the ''[[VideoGame/SenranKagura Senran Kagura]]'' anime shows [[TooKinkyToTorture Ryōna]] is so "experienced" with rope that she can even tie herself up, bondage style. This is presented as just another gag of how perverted and masochistic she is. [[spoiler: But when a giant yōma proves to be impervious to attack, Ryōna busts out a giant rope and quickly ties it up.]]

* In the ''Manga/HetaliaAxisPowers'' [[TheMovie movie]], In the beginning of the movie, Italy is seen scribbling funny faces on the photos of TheFaceless [[AlienInvasion aliens]]. It turns out to be the key to defeating them.

* In the ''Manga/AxisPowersHetalia'' [[TheMovie movie]], In the beginning of the movie, Italy is seen scribbling funny faces on the photos of TheFaceless [[AlienInvasion aliens]]. It turns out to be the key to defeating them.

* ''Manga/OnePiece'' is fond of this, though how critical the Chekhov's gun is varies per use. Among examples are a rather odd pinwheel worn in the hat of Genzo, the sheriff of Nami's home village. This pinwheel has three Chekhovs to its name. First, it inspires the attack Luffy uses to remove the villain-of-the-arc's giant sea cow from the fight. Second, along with Bellemere's tangerines, it forms the basis for Nami's new tattoo. But the true Chekhov comes at the end, when a flashback reveals that Genzo put the pinwheel in his hat to make the then-baby Nami laugh. To everyone's surprise, it worked, and so Genzo continued to wear it as a way of supporting Nami as she struggled, removing it only when Nami left with the Straw Hats.
** The concept of Haki is a good example of this. In the very first chapter, Shanks is seen scaring a Sea King away simply by gazing at it. More than four hundred chapters later, the power is named but is not elaborated upon. Luffy is later seen unknowingly using a similar gaze on Duval's Bull, and it isn't until five hundred chapters in that the concept of Haki is fully explored.
** In the Davy Back Fight [[StoryArc arc]], Luffy is outfitted with an afro, thinking that it will make him stronger in his upcoming fight. Then, at the end of the fight, a shard of mirror caught in the afro proves crucial to his victory.
** Luffy's brother gives him a piece of blank paper early on in the Arabasta arc. The paper's purpose is left unknown for ''several hundred chapters/episodes'' (depending on whether you follow the manga or anime.)
** The third movie has Usopp use an actual boomerang in order to attack the BigBad, but as it turns out, it was fairly useless. However, it's later used to lure a bunch of Horn Eaters belonging to the big bad, by imitating a pair of horns, into a ravine, where they are trapped.
** Oda seems especially fond of this trope. Early on in the story, our beloved pirate/clown Captain Buggy is looking for the treasure of one Captain John. A long long long way down the line during the Thriller Bark arc, Captain John's zombie turns up. After the conclusion of this arc, Buggy's self-proclaimed rival Luffy finds a cool armlet in the Thriller Bark treasure hoard, which stays with him for about forty chapters before he and Buggy end up in Impel Down together. Only THEN, do we realize that the armlet Luffy took is in fact the key to finding the long lost treasure that Buggy has been looking for all along!
** One word: Laboon. The crew meets him just after they've entered the Grand Line, and it is mentioned that Laboon is waiting there for a pirate crew he befriended to come back. Several hundred chapters/episodes later, they gain a new crew member (Brook) who just happens to be the only remaining member of that pirate crew and his goal is to keep his promise that he'll come back to see Laboon again.
*** Even earlier than that, starting back in the Arlong arc, Luffy starts saying that their next crew member needs to be a musician. Guess which role in the Straw Hats Brook fills.
** Captain John's treasure was predicted right after the chapter he picks it up at was released, so it wasn't a huge shock. Still the Captain John plotline is relatively low-key, but is probably another set up. When it was first shown it was just thought to be a random thing to let us check in on Buggy, and the real important event was Ace showing up on his ship. No doubt Oda is the king of this trope. Laboon and Crocus in particular have a lot of events connected to them. It seems everything after they arrive in the Grand Line has had some kind of purpose later on. The sheer impressiveness comes when you realize that some of these set-ups took more than a decade to complete.
** Early on, we can see that some of the Arlong Pirates seem to have a second, sun tattoo in addition to the one that identifies them as part of the crew. Hundreds of chapters/episodes later one, it's revealed that this links to another, legendary pirate crew, the Sunny Pirates formed by Fisher Tiger from freed Fishman slaves with the aforementioned sun tattoo (actually a brand) being their symbol as well as a way to cover up the brand they received as slaves. The whole slavery angle ties in to the whole Fishman/Human racism dynamic that underpins the Fishman Island arc.
** During a flashback in the Fishman Island arc it is mentioned that the Royal Family possesses a treasure capable of rapidly aging an individual. At the end of the arc it is revealed that the mysterious treasure was actually the Energy Steroids the New Fishman Pirates had been using to boost their strength. Once the effects wear off they are left decrepit and old.
** In the title pages of most manga chapters we have sidestories depicting the adventures of Luffy's previous enemies after their encounter with the strawhats (Buggy, Hachi, etc.). If you still think that any of those are supposed to provide closure to those characters, then you didn't pay attention.

* In ''Manga/BlackLagoon'', the pistol Balalaika used to slay [[spoiler:Boss Kousa]] and then threw into the ornamental pool is clearly shown to have a fingerprint on it, presumably Rock's from when she handed it to him. It's likely this will bite Rock later on in the series. Another additional meaning is to represent that Rock can never return to his home country, due to his status as a prime suspect in the murder of a Yakuza boss.

** Another example of the Future Trunks arc: Early on, Goku is given a button by [[TopGod Zen'o]] so that he can call him down whenever needed. Sure enough, in the final episode of the arc, [[spoiler: Goku uses the button to deal with Zamasu after he transforms into an EldrichAbomination.]]