Right after the Female Titan is initially immobilized Levi's squad and Eren have orders to keep riding forward and later discuss how huge this accomplishment is. This happens shortly after the Female Titan breaks out and is on the loose looking for Eren...
Before the Survey Corps returns from the 57th expedition, the audience is treated to shots of the families of Petra, Eld, Gunther, and Oluo anticipating their return. The audience on the other hand knows what happened and it makes it heartbreaking to watch.
Berserk: The entirety of the Golden Age arc serves as this. We see Guts grow from a cold loner who suicidally throws himself himself into battle into a man who finds peace among his comrades. And he forms a strong friendship with his leader Griffith. Shame its a flashback after 3 volumes of Guts as a vengeful cold loner who suicidally throws himself into battles against apostles in his vendetta against Griffith who has become a god.
A Certain Scientific Railgun has a scene in which the members of Scavenger discuss the legend of a Level 0 esper who's encountered multiple Level 5 espers. They laugh about it, thinking that there's no way a Level 0 could run into multiple Level 5s and still be alive. The Level 0 in question is Touma, a recurring character and the main character of the original series.
Played up for all its worth, coming to its head in episode 16 (the one before all The Masquerade started to unravel). That episode featured a conversation between Princesses Cornelia and Euphemia about how much Prince Clovis cared about his dead little sister and brother and how capturing Zero would avenge the deaths of all three of their siblings- Clovis, Lelouch, and Nunnally. Not only are the latter two still alive, but Lelouch IS Zero — and worst of all, Euphemia's reactions in previous episodes show that not only is the audience aware of the irony, but she's catching on to it, too. It also saw Kallen saying she has no interest whatsoever in him, though she is infatuated with Zero, who is arguably more the real Lelouch than Lelouch is. But the highest amount of irony had to do with the interaction between Lelouch and Suzaku which saw the two of them teaming up to defeat Mao and save Nunnally, they said they trusted each other completely and agreed to help protect each other, completely unaware of the other's Secret Identity.
Lelouch hoped Suzaku would help protect Nunnally, but it turns out that he can't because he's the guy piloting the Knightmare that's been giving him so much trouble as Zero.
He later spends a ridiculous amount of effort (all his effort) trying to get her back by kidnapping her once she's become Viceroy of Area 11, only to realize once he has her that he doesn't have any idea of what to do, and Suzaku's her knight (just as Lelouch hoped he'd be before, but for the other side), and it appears to all have been for nothing once she "dies" during the FLEIJA's detonation. And it's not until after he thinks she's dead that he realizes he'd been using her as an excuse to prioritize his life before others'; to feel as if he had a right to be proud of himself.
All the effort Suzaku and Lelouch spent trying to rescue Shirley was for nothing once Rolo murdered her.
The whole reason Lelouch uses Geass is to invokethis; if soldiers with guns prepare to kill you, you can take their lives, if one of your friends wants a reason to die so as to redeem/punish himself, you can force him to live, and if a despotic Evil Chancellor wishes to oppress humanity's will to create a world without crime where people wouldn't honestly give a damn about each other and only act kindly out of fear of the law, you can take away his ability to act in accordance with his will.
The man Jeremiah most desperately wants to kill is the man he most desperately wants to avenge.
Shirley seeks sympathy for her father's death in the arms of the man most responsible for her father's death.
In Deadman Wonderland, Ganta's relationship with Shiro is more of a combination of creating tension and making the audience cringe on his behalf. The situation being that the Red Man killed all of Ganta's friends and framed him making him have to go to prison, making Ganta want to kill the Red Man for revenge. In prison, Ganta becomes really lonely, and comes to rely on and bond with Shiro. The one time he doubts her, he is proven very wrong, and makes a promise to himself that he'll believe in her from now on. Only thing is, Shiro turns out to be the Red Man. The audience can only imagine what his reaction will be when he finds out... He doesn't take it well.
The Anti-Kira Taskforce sees L as a stubborn Inspector Javert who is unreasonably convinced the Chief of Police's son Light is the killer, despite all evidence to the contrary. Of course, as the audience, we know he's right.
A more specific (and brutal) example when Light's biggest obstacle L dies; Light can scream and panic and Freak Out to his heart's content, but the audience is well aware who is responsible... though perhaps not entirely sure how genuineit is.
When Light's father is killed, this happens again; having made the Shinigami Eye deal, the Chief looks at Light and dies declaring his relief that Light isn't the killer after all... but the audience knows it only appears that way at the time, and that, in actuality, Light has been the murderer all along.
The Yotsuba arc is full of this: Light uses loopholes in the rules of the Death Note to absolve himself and Misa of their identities as Kira, wiping their memories of everything related to the Death Note, and tells Rem to give the Death Note to someone who will use it selfishly and make himself easily noticeable. Over the course of the arc, Light — now allied with L — pieces together how Kira's powers work and they catch the third Kira, Higuchi. True to form, it was all part of a massive Batman Gambit so that Light would eventually get his hands on the Death Note again and go right back to being Kira, ultimately allowing him to indirectly kill L. Naturally, the audience is already privvy to this even if they don't know exactly what Light's plan is.
In Delicious in Dungeon, the Lunatic Magician is desperately searching for the king of the Golden Kingdom...who the reader saw crawling up to the surface and promptly crumbling into dust. On the first page of the series.
In Detective Conan, Ran believes Shinichi has gone missing and doesn't know that he's actually been turned into the little boy who now lives with her, which leads to a lot of scenes where she reminisces about Shinichi and wonders where he is while standing right next to him. She comes close to discovering his secret on more than one occasion, but this always leads to Shinichi finding some way to throw her off.
In Digimon Adventure at the very end of her introduction episode, we see Kari's digivice letting us know that she will also be called into the Digital World. The story arc that starts six episodes later is about the characters trying to find the 8th child, not knowing that the 8th child is their leader's little sister (though Tai briefly suspects).
Goku does this again (awesomely comically) in the leadup to the second World Tournament arc. Everyone is chiding Goku for just making it in time to register... until they learn of the journey he took to get there. First, following Roshi's advice, he refused to use his Nimbus to travel to Papaya Island. Surprise #1: He swam all the way. Surprise #2: He swam from Yahhoy...on the opposite side of the planet! Probably a good thing they didn't learn Surprise #3: He did it in only three days.
Byakuya thinks the ISS and his Robot Buddy Rei have gone down into the earth's atmosphere and been destroyed. Meanwhile Rei is still active in space onboard the ISS trying to keep it in orbit until Byakuya returns. Rei decides to send a light signal to Byakuya to show him that it's still alive and waiting for him. Byakuya realises that his friend is still alive and waiting for him, but unfortunately he dies before he can tell anyone about it.
Natsu spends a good portion of the Nirvana arc chasing down a resurrected Jellal to keep him from meeting Erza, not knowing that Jellal has lost his memories and, in fact, has encountered Erza by the time Natsu finds him. Even after Erza talks him into having a Heel Realization, Natsu still thinks he is another enemy on the loose. This trope then becomes doubly subverted: Jellal regains his memories of Natsu shortly before running into him again, and the readers are led to believe he has reverted to his evil ways, only for it to turn out otherwise when he gives Natsu a Power-Up that helps him defeat Zero.
A minor example occurs when Raven Tail's master Ivan smugly watches Gajeel enter the Grand Magic Games as a member of the Fairy Tail guild. Here's where the irony lies: Ivan believes that Gajeel is spying on Fairy Tail for him, when the readers (and at least Makarov) know by this point that Ivan has it totally backwards. In fact, by the time Gajeel first meets Ivan, he already considers himself to be a member of Fairy Tail through and through.
A more extreme example takes place during the same arc when Erza bumps into her childhood friend Millianna during the games. Their happy reunion is spoiled when Millianna brings up her burning hatred for Jellal and desire to see him dead for killing their friend Simon, and assumes Erza feels the same way, not knowing that Erza has already rekindled her friendship with Jellal and, in fact, expressed her mutual feelings for him. The tension rises once Millianna finds out that Erza and the rest of Fairy Tail have been secretly harboring Jellal during the games.
Perhaps the biggest example of this is the reveal of the true identity of E.N.D., the strongest Big Bad of the series. His real name? Natsu Dragneelnote EtheriousNatsu Dragneel. It's further compounded in Gray's case, since he repeatedly expresses his desire to destroy E.N.D., not realizing that he's talking about one of his closest friends.
When Gray defeats Invel and then goes to fight Natsu/E.N.D., he repeatedly says that he's fighting to avenge Juvia's death, not knowing that Juvia actually survived.
The first opening song for Fate/Zero is a rather upbeat and positive sounding number. By the end of the story, all involved participants are dead, emotionally destroyed, or both.
In Fist of the North Star, Juza, one of the guardians of the Last General of Nanto, dies while fighting Raoh after refusing to divulge the General's identity. However, it's Juza's very sacrifice that causes Raoh to realize the General's true identity.
During the early arcs of Food Wars!, main character Soma Yukihira is constantly antagonized by Erina Nakiri, who refuses to acknowledge his culinary skills and takes every chance she can to get him expelled from the academy. Little does Erina know, Soma is the son of Joichiro Saiba, the only chef she's ever admired, so Erina unknowingly has been insulting and demeaning her idol's culinary style.
Fullmetal Alchemist fulfills this trope from very early on as in Scar's first appearance early. Another big one is Ed and Winry talking about Lt. Colonel Hughes right after his death, when Ed mentions that despite finding Hughes annoying, he likes him and wants to see him again some time. The brothers don't hear of his death until some time later, after they return to Central.
Mobile Suit Gundam 0080: War in the Pocket milks this trope for every drop it's worth. The series has a cute romance brewing between Christina and Bernie, neither of whom knows that they're enemy soldiers or that Chris is test-piloting the Gundam that Bernie's team has been ordered to destroy at all costs. Turns absolutely gut-wrenching in the final episode, where each of them asks their mutual friend Alfred to say "goodbye" to the other for them; at this point Al is in on the secret, having witnessed Bernie destroy the Gundam (badly injuring Chris in the process) at the cost of his own life.
There's a nice example in ∀ Gundam where one of the excavation teams digging through one of the silos discovers a rack of torpedo-shaped objects with the radioactive trefoil symbol on it. The audience obviously realizes they're nuclear bombs, but the characters have no idea what the symbol means. Cue lots of squirming as the characters repeatedly drop and otherwise shock the bombs.
In Mobile Suit Gundam 00, the character Allejuah has an evil split personality which was implanted in him as a child. One episode has a flashback of him as a child, showing his first meeting with his childhood sweetheart who comments on her efforts to communicate with him even though she was essentially being kept catatonic previous to that. He makes a comment on how it must have worked, as he heard her voice in his head. The audience realizes that wasn't actually her voice, but rather the beginnings of the split personality.
The "audience is in on the joke" type is present in one scene of the Gunslinger Girl anime and manga. Franca, a bombmaker working for the terrorist group Padania, accidentally bumps into Henrietta, one of the titular cyborg assassins assigned to eliminate her group. Neither is aware of what the other is, and after the encounter Franca is briefly reflects on how glad she is that one of her allies' plans to bomb that area was thwarted, because "protecting children like her is what Padania is all about."
In In This Corner of the World the main character Suzu moves from Hiroshima to Kure during World War II. Later on her sister suggests she returns to Hiroshima, because Hiroshima is not nearly as heavily bombed as Kure.
During Initial D Second Stage, Bunta makes it a point several times that the Trueno's original engine is close to the end of its life, a fact that he decidedly does not tell Takumi because he plans for the engine to go out so that Takumi can better appreciate the planned engine swap. Takumi goes on to race against Kyouichi unaware that the Trueno's 4AGE engine is about to blow, the race interspersed with shots of the Trueno's engine and Bunta's commentary on the soon-to-be-gone engine and the engine swap. Sure enough, the engine blows apart in mid-race, with Takumi naturally horrified about it.
Both Ishigami and Iino helped each other back in middle school, and neither is aware that the other did so. Ishigami sent Iino an anonymous letter of encouragement that continues to inspire her in the present, and Iino protesting Ishigami's continued suspension is what allowed him to graduate.
At the end of chapter 12 of We Want to Talk About Kaguya (set just before chapter 14 of the main series), Karen and Erika comment on how pure Kashiwagi was. The chapter of the main series that came out that same week (set about five months later) had her getting caught making out with her boyfriend in a locker, to say nothing of their implied to be very active sex life.
We Want to Talk About Kaguya is built on this, as most of the humor relies on the reader knowing what happened in the main series and seeing Karen and Erika grossly misinterpret it.
Sora of Kaleido Star tends to bumble into situations, setting her up for the cringe-inducing variation. Having just been accepted into the Kaleido Stage, she runs up to her new colleagues, energetic, happy and ready to introduce herself. The viewers, however, have just seen that the other troupe members are suspicious of Sora for the very untypical way she came into the picture and mistakenly think that she actually cheated her way into the circus. The audience isn't surprised when they shun Sora and lumber her with all the cleaning duties as "punishment" — but Sora is.
Karakuri Circus: During the finale, Bai Jin tells Masaru that he'd have to meet Francine again if he went to Heaven. The reader knows that she actually killed herself believing that she'd go to Hell.
From the very beginning of Magical Girl Lyrical Nanoha A's the audience is aware that Hayate is the Master of the Book of Darkness. This is used as a joke in episode 6 when Nanoha and Yuuno discuss what type of person the master might be, Nanoha even wonders if it's someone their age (which Yuuno dismisses). She then receives a text from Suzuka, who wants to introduce her to her new friend... Hayate.
In Mazinkaiser Baron Ashura disguises him/herself as Professor Yumi in an attempt to blow up the Photon Power Laboratory, but ends up at the Professor's surprise party instead. Kouji, Sayaka and Boss give him an asymmetric suitnote Baron Ashura's body is noticeably asymmetrical., a bouquet of foxgloves (meaning 'two-faced') and a dartboard with Ashura's face on it. Baron Ashura starts to suspect that they're doing it on purpose.
During a flashback chapter, Tohru tells a bandit that she'd never let a human ride on her back. In the present day, she often complains about how Kobayashi refuses to ride her to work.
After Tohru showed up in retaliation for him hurting Kobayashi, Clemene tried calling Elma for help. It's far more likely that — if Elma had shown up — she would have struck an Enemy Mine situation with Tohru and killed him instead due to her own relationship with Kobayashi.
Seo and Wakamatsu's relationship in Monthly Girls' Nozaki-kun is based on dramatic irony. For starters, he dislikes and barely tolerates her, but is in love with Lorelei after only hearing her voice, except Seo is Lorelei. Nozaki can be seen first cringing and then curled up in mortification when Wakamatsu begins talking about how great Lorelei is to Seo, intending it as an insulting comparison. Later, several characters begin shipping their manga counterparts together, apparently including an oblivious Wakamatsu!
When Midoriya makes Shoto use his fire powers in the U.A. Sports Festival, Endeavor starts loudly cheering for Shoto and boasting about his power. To the crowd, he seems like an affectionate father openly showing how proud and supportive he is of his son, something that Present Mic even lampshades, but he's an abusive father who has been physically and emotionally abusing his family ever since Shoto was 4. The abuse was what prompted him to deny the fire powers he inherited from his father in the first place.
The viewers find out very early on that All Might's health is secretly declining from an injury he suffered years ago and that his days as an active hero are numbered. The fact that he keeps his condition a secret and keeps up his image as an invincible paragon leads to this in a lot of characters whose goal it is to defeat or surpass him, not knowing he won't be in their way much longer. The most notable example comes from Endeavor. All Might suddenly announcing his retirement after almost completely losing his powers does not sit well with Endeavor, who did some truly despicable things in pursuit of surpassing All Might to become the #1 ranked hero, only to have all of those actions rendered meaningless by simply inheriting the #1 spot because of All Might's retirement instead of having actually earned it for himself. The good news is, this hits Endeavor with some Heel Realization and prompts his attempt to change himself for the better.
A minor example occurs during the Joint Training Arc, when Monoma manages to use his Power Copying Quirk on Midoriya, thereby gaining the power of One For All. It has no effect because One For All is an extreme example of Magikarp Power and is built up in strength over generations, and Monoma can only copy Quirks at their base level for five minutes at a time. Monoma is disappointed it was a dud, but Midoriya and the audience realize that he was lucky that it was a dud, or otherwise he would have been turned to Ludicrous Gibs.
A rare examples of this being applied to the bad guys: Kakashi managed to track down Sasori and Deidara using a piece of cloth Kankuro managed to yank from Sasori. When they hear Kakashi's team is approaching, Sasori immediately says this must have been Deidara's fault.
And then done to Naruto and Sasuke when, in a flashback, their mothers talk, figure out that Naruto (who wasn't born yet) and Sasuke will be in the same grade, and they hope that the boys will be friends.
Chisame tells Negi about how she doesn't believe a word of the "urban legends" around the school. Naturally, all of them are completely true, and Negi was directly involved in most of them (she does, however, note that he's a bad liar). There's an additional layer of irony in that Chisame herself eventually ends up dealing directly with just about everything she mentions.
Episode 17 of ("Fourth Children") is a textbook example of dramatic irony. At Shinji's expense, of course. Everybody except Shinji knows that Touji is the Fourth Child, and the plot of the episode is centered on the fact that everybody conceals that fact from Shinji (either intentionally or unintentionallynote Asuka, for example, had mistakenly assumed that he knew all along, and when she realized during the sortie that nobody bothered to tell him even now, she was started to spill the beans to him before she was cut off by a surprise attack from the Angel.) until it's too late.
And then you have the scene where Shinji and Asuka kiss. Asuka liked Shinji and she wanted to kiss him, but she treated it like a game to waste time in case he was going to reject her bysaying she was bored and pinching his nose. Since Shinji stood still, gasping for air instead of kissing her back or hugging her, she thought he had rejected her and ran off. The sad thing is Shinji DID like Asuka, but because she was treating it like a game, he did not think she liked him back and he did not dare to do anything. So instead of getting them closer, their kiss made Shinji feel worse about himself and contributed to Asuka's breakdown (that scene played during her Mind Rape).
In Rebuild of Evangelion, those who have seen the original series — and who see that Asuka has been chosen to be the pilot of the new Eva — have to watch in horror as the poor pilot is made to go through sudden and unexpected Character Development just before sitting down in front of the controls to make the incident more dramatic.
Another major source of it is that those who have seen The End of Evangelion now know that Gendodoes care about his son and honestly loved his wife, which Shinji still has no clue about. That makes certain scenes a whole lot more painful. The movie itself shows him having a flashback of his wife and ordering his driver to do an u-turn mere metres from where he might have picked Shinji up as he is informed about the whole EVA 03 business, but Shinji himself sees neither and, after some unfortunate circumstances, declares that he hates his father and that he needs "needs to lose someone important as well so he knows how it feels.". Ouch.
Omujo! Omutsu Joshi: A big part of the dynamic between Shouta and Morei is that each believes the other has a fetish for diapers when, in fact, neither of them do. Morei jumps to this conclusion after she witnesses an Accidental Pervert moment between Shouta and Ichigo, a girl so prone to Potty Failure that she needs diapers. This prompts Morei to try appealing to Shouta by wearing a diaper herself and unwittingly convinces Shouta she's the one with the fetish.
Done for suspense when the readers are made aware of Ace's capture and planned execution while Luffy blindly dodges newspapers with that information on it.
In a later arc, Donquixote Doflamingo brags that he's trapped Luffy in his coliseum with no escape, and that the Straw Hats will never find his black market harbor, unaware that Luffy's already ditched the coliseum to attack Doflamingo's castle, and that Usopp and Robin are already in said harbor and planning to take down his most important minion. The real irony is that earlier Doflamingo claimed Luffy's earlier successes were due to his opponents underestimating him.
Used earlier in a heartbreaking way during the entire Alabasta arc with both the rebel army and royal army vowing to eliminate the other, not knowing the war was instigated by Crocodile.
Used both humorously and awesomely during the Enies Lobby arc. For the majority of the arc, Spandam was under the impression that the Straw Hats had been slaughtered without even making it past the island's gate, due in part mostly to his Transponder Snail being off the hook, unaware that not only had the Straw Hats managed to reach the courthouse, but they had also turned the island's giant gatekeepers against the Marines and caused over 2,000 casualties, resulting in the very first crisis in Enies Lobby's history. Upon finally getting word that the main island was calling him, Spandam believed that it was a report on the Straw Hats' defeat, which he mocked Robin in the face over before answering. His reaction upon learning the truth was gratifying to both Franky and the audience.
In the Third Act of the Wano Arc, Shogun Orochi believes he's stopped the heroes' army from attacking him and Kaido on Onigashima. Naturally, he's completely unaware that the sabotage attempts have failed, and that a five thousand-man army has landed on the island and preparing to assault Kaido's mansion. When he learns from his spy of what's happened, another minion assured him that they haven't found any ships...because the samurai sank their ships they used as part of their Do Or Die mentality. At that point, Orochi isn't accepting any assurances.
Anytime King gets praised for his heroic feats after Saitama finds out that King is just a baseline human who just happened to be near Saitama's unrecorded victories against monsters. In reality he's just an otaku who wants to play his games in peace, and his abilities are just a side effect of his fear (he's The Stoic because he's doing his hardest not to show how terrified he is, and the "King Engine" is actually his heart beating louder when he's scared, not because he's ready to fight).
Child Emperor comes up with a device that reads Power Levels. Naturally, he's confused as to why King's and Saitama's readings don't show up at all (too low and too high respectively) and guesses he made a calibration error. If only he knew...
Pet Shop of Horrors loves this trope. Chief among various uses of dramatic irony are Leon's many assertions that the supernatural-thing-of-the-chapter can't be real, because magic doesn't exist...right before he stops by for tea at Count D's pet shop, where the supernatural-thing-of-the-chapter is probably in one of the rooms in the back.
In Phantasy Star Online 2: The Animation, Itsuki marvels at how lifelike the game's non-player characters are. Rina explains that the AI in the game is highly advanced. Little does she know, they're real people: the universe of PSO2 is completely real and only presented as a game to Earthlings...
Played for Laughs in Please Tell Me! Galko-chan. Chapter 10/ the Is it true that there's a psychological test that evaluates how you have sex? skit in episode 5 depends on this trope. The boys and the viewers knows how to interpret the girls' answer to an seemingly innocent question as their sexual practice preferences, but the girls never know about that fact.
This also applies to Ash and his friends who were previous unaware that "Squishy" was actually the immensely powerful Zygarde, with Team Flare, Team Rocket, the audience, and to a lesser extent Pikachu being the only ones fully aware of the fact. It was only after Team Flare's plot began that Ash and his friends learned the truth themselves, much to Bonnie's surprise.
In Puella Magi Madoka Magica, Sayaka blames Homura for Mami's death, believing that Homura chose not to interfere, thus leading to Mami dying. But the audience knows that Mami herself had cast a binding spell on Homura prior to the fight, meaning Homura couldn't have stepped in until the spell was broken by Mami's death.
Played for brutal tragedy in RahXephon when Ayato gives a Declaration of Protection to Asahina as he goes off to defeat a Dolem. What he doesn't know is that the Dolem is in sync with Asahina so everything he does to the Dolem hurts Asahina in the same fashion. And it twists the knife even further he does this while she's trying to confess her feelings to him. Worse yet, everything she writes shows up in every electronic screen in the area. Ayato fails to notice this until he delivered a killing blow, and turned to see her final message on a building and realized what he had just done.
Much of the conflict in Rent-A-Girlfriend comes as a result of Kazuya lying about Chizuru, a "rental girlfriend" being his actual girlfriend, as well as keeping her profession a secret. As a result of this, many characters are unaware of things that the audience knows quite well.
One example comes when Kazuya's friend Kuri invites Kazuya and Chizuru to a double date with himself and his new girlfriend Ruka. Kuri is later heartbroken when Ruka betrays him by exposing her own identity as a rental girlfriend in front of Kazuya, whom Kuri assumed didn't know, and Kuri bitterly assumes that Kazuya doesn't get what it's like to have to rent a girlfriend. In reality, Kuri is mistaken; Chizuru is a rental girlfriend and Kazuya had inwardly felt a bit jealous of Kuri at the double date, when he didn't know about Ruka being a rental girlfriend.
Some time later, Kazuya's father Kazuo confronts him and accuses him of borrowing money from Chizuru, having seen money change hands between those two. In reality, Kazuya was paying for Chizuru's rental fees, which means that in reality, he's given her a large amount of his money.
Revolutionary Girl Utena runs on this, especially rewatching the series. It's terribly heartbreaking at times. Also the shows of "sibling love" between Akio and Anthy to Nanami. It's hilarious as well as very, very disturbing.
In the The Saint's Magic Power Is Omnipotent, after the protagonist Sei finds herself transferred to another world against her will, she spends several weeks in the royal castle bored, without company except for one maid, and no visitors whatsoever. She thinks that the locals have forgotten about her because she was not the "Saint" they were hoping to summon, but in reality, the kingdom thought she was seriously ill (thanks to her exploitative office job) and the best thing they could do was leave her well alone to recover.
In the English dub, the audience knows that Serena is the Moon Princess from the very first episode, but the characters don't learn this fact until episode 30. This dichotomy is also utilized in the Crystal remake.
Usagi: Sailor V is the princess! I knew it!
In Sailor Stars, Usagi writes many letters to Mamoru—who she believes is studying in America—and sometimes the letters even provide narration for the episode. However, the audience has known that Mamoru was dead from the moment it happened. To make things even worse, Rei's last words to Usagi are that she "still has Mamoru".
s-CRY-ed has an interesting variation, in that the irony's never really brought up until it's rectified; there's really nothing to tell the audience that Kanami doesn't know Kazuma's an alter user, but the pieces definitely fall into place once it's revealed. Also sets the stage for a bigger one that reverses the roles: the fact her dreams are so lucid and accurate are the first clues that she is an alter userthe dreams are the manifestation of her power.
Superior is built on this since the audience is aware from the very first page that the demon queen that Exa has sworn to kill is his traveling companion Sheila. A good chunk of the tension in the series comes from her trying to keep this a secret as she slowly falls in love with him.
In the second arc, Leafa is helping Kirito reach The World Tree. She's slowly falling in love with him (as tends to happen), unaware that he's on a quest to rescue his wife. On the other hand, they are both unaware that Leafa is actually his cousin, due to the anonymized nature of virtual reality. So she really never had a shot with him. In fact, Suguha is trying to get over her crush on her cousin, Kazuto, since they're adoptive siblings and he already has a girlfriend, so she knows Kazuto's taken, but doesn't know that about Kirito. The whole thing is presented as a tragedy, and is often described as "a train wreck in slow motion."
In Volume 13, Kirito and Eugeo are separated while climbing Centoria Cathedral, after Kirito and Alice are forced outside. As Kirito and Alice climb the outside of the building, Kirito's relatively optimistic about Eugeo's chances, noting that Eugeo has much greater talent and potential than he does. Unbeknownst to Kirito, Eugeo, who continued climbing inside the building, got captured by Prime Senator Chudelkin, given a Breaking Lecture by Quinella, and ended up being turned into an Integrity Knight, and Kirito doesn't realize the full truth until he sees Eugeo again.
Tamagotchi: In "Rednosetchi is Lost!", Mametchi, Chamametchi, and Hapihapitchi help Rednosetchi to find Santaclaustchi, who is getting help from Memetchi and Kuchipatchi to find Rednosetchi. The two groups are quite close to each other as they look for each other to begin with, but later in the episode there's a scene where Santaclaustchi and Rednosetchi are sitting on opposite ends of the same fountain and never realize the other is literally right behind them as they worry that who they're looking for doesn't care about them anymore. They decide to go different directions to find each other... which somehow works as they meet at the front of the TAMAX-TV building.
In Toilet-Bound Hanako-kun, after chapter 27, everyone, including the readers, know that Nene will lose her life in one year, except the latter.
In the Duelist Kingdom season of Yu-Gi-Oh!, when Joey is in danger of being disqualified because he lost his entry card, the audience are the only ones aware that it's because Bandit Keith stole the card the previous night.