20th Century Boys (or, for the final 16 chapters, 21st Century Boys) is a manga series created by Naoki Urasawa, the mastermind behind Monster. The plot of the manga spans several decades, from the 1960s to the 21st century, and involves a large cast of characters and several plot twists along the way.It's the year 1997, and Kenji Endou's life is going to change forever. As a youth, Kenji harbored dreams of becoming a rock star; now, however, he's stuck working in his late father's convenience store (formerly liquor store). On top of that, his older sister has disappeared and has left Kenji to take care of her infant daughter.One day, Kenji learns that a childhood friend of his, nicknamed Donkey, has committed suicide by jumping off a roof. Shortly after the wake, Kenji receives a belated letter from Donkey, including a drawing of a strange yet familiar symbol and the question "Do you remember this symbol?" along with a request to get together some time.The letter convinces Kenji that Donkey's suicide was, in fact, a murder. In his efforts to unravel the mystery behind his old friend's death, Kenji learns of a man known only as Friend who is the founder of a very popular cult. A cult that uses the symbol shown in Donkey's letter, a symbol that was in fact used by Kenji and his friends back when they were kids.During their childhood, Kenji and his friends played a game in which they imagined the world being destroyed by a group of villains. Now, Kenji must gather his friends again, in order to prevent Friend, the man who took their symbol, from turning their childhood fantasies into a horrible reality.Adapted into a live action film trilogy that is among the most expensive Japanese film projects in history. The films are very faithful to the manga (until the end, at least), which has inevitably led to criticism that they're impossible to follow if you haven't read it, due to time constraints forcing some important characters into smaller roles. Rather surprisingly, an Animated Adaptation of the series was never planned.
This manga contains examples of the following tropes:
Abandoned Hospital: Kanna finds out some information about her mother in one. It isn't really a creepy one, though.
Agent Scully: As a child, Donkey firmly believes in science over superstition.
Apocalypse How: Deconstructed and Reconstructed. At first, the heroes want to stop the Big Bad from doing a class 3. Turns out it was only a class 0, designed to frame the heroes for it and make the Big Bad more powerful. 15 years later, the Big Bad pulls out a real class 1, kills about 90% of the humanity, and conquers the world. And 3 more years later, he tries to do a class X, only to be finally stopped by the main character. But it doesn't end here: after the Big Bad's death, one of his followers tries complete his master's plan, and do the class X, but is also stopped by the heroes.
Apocalyptic Log: Kanna finds a note her mother wrote in an abandoned hospital, referring to her involvement in creating the virus: "I am Godzilla, I crushed 300,000 under my feet"
The Blank: Friend occasionally appears as this after the mask is taken off. Justified as it's only in a virtual reality program.
Boke and Tsukkomi Routine: Two of Friend's followers are a manzai comedy duo who spread Friend's blood-hemorrhaging biological weapon to Osaka.
Book Ends: The first and last chapter of the series both show the scene where Kenji puts "20th Century Boy" on the PA, although in the last chapter you see it from a different point of view.
Not quite the last chapter, but at the start of the series, there's an enigmatic scene with a girl waking up and looking out her window and seeing a giant robot staring at her. In the penultimate chapter before 21st Century Boys, that scene is finally given context.
Call Back: Loads of them throughout the series. For one thing the sheer amount of characters who're shown early in the series and make appearances in the last arc is staggering: it's clear Naoki Urasawa is not the kind of guy who simply forgets about even the smallest of characters and events.
Calling the Old Man Out: Kanna manages a pretty good one against Friend late in the series. Subverted in that her father is dead by this point, and the man behind Friend's mask is an impostor.
Card-Carrying Villain: Moroboshi's killer. There's even a scene of him comparing himself to various old anime villains.
Compressed Adaptation: The second and third films, due to their having to cover far more chapters of the manga than the first.
Cult: Friend builds one up around himself that gradually grows in both size and intensity, up to the point he pretty much takes over the world.
Darkest Hour: Chapter 169: Friend is now hailed worldwide as a 'God', and has just released a new virus, killing several million people. It would be even more depressing were it not for the epic He's Back moment in the next chapter.
Friend himself is a thorough deconstruction of the Evil Overlord character archetype. Flashbacks reveal the first man behind the mask believed himself a special person since childhood and, once shown up by his schoolmates, decided to prove them dead wrong. He does so at first by exploiting other people's need for a savior/messiah to make himself one, then frames the real heroes for his nefarious plans - the plague-spreading mecha - to take over Japan; and finally frames himself as a hero by "coming back from the dead" and "saving" the Pope, thus assuming enough power to become President of the world. And none of it would have happened had he not also used his underlings' desires and wishes to keep them loyal to him almost to the bitter end.
Defector from Decadence: Many major supporters of the first Friend decide to betray the second one and help the protagonists. Not so much because they realized that they're wrong but because they truly believed in the real Friend and not an impostor.
Disproportionate Retribution: At the very end of the series, we finally find out that the reason why the impostor Friend was trying to destroy the world and it all started when they were children, and Kenji stole a plastic toy badge from a local store and let him take the blame for it.
Don't forget The first Friend. The reason that he became Friend in the first place was to get back at Kenji and his friends for showing him up when he was a child.
Arguably, Friend was also a victim of this. To have the rest of the kids in his neighbourhood treat him like a dead man, to the point that they can't remember that he didn't actually die, over stealing a cheap plastic toy? That's cold.
Enemy Civil War: After Friend is replaced, Manjoume starts planning a coup. After Friend publicly admits his atrocities, most of his army up and rebels.
Faux Symbolism: An in-universe example is revealed with Otcho's explanation of how he came up with the symbol that later became the Friend group's: he took the "continue on the next page" marker and drew an eye over it.
Flash Forward: The first chapter has one with grown-up Kanna seeing Shikishima's new robot outside her apartment in 2018, which doesn't happen until the penultimate chapter, not counting the two volume epilogue.
Go Mad from the Revelation: The reaction to the bonus stage at Friend Land, specifically the boy in the mask having a grown man's head.Kyoko only managed to see it and not kill herself because her memory was damaged from being removed and only gradually returned.
Gratuitous English: Crops up a few times in the story itself but most notable in the pre-volume title pages. For example: "Kyoko met Kenji of his boyhood, and saw something she should never seen ... it was the face of the "Friend"!! Who will survive the world of indistinguishable of friend and foe to the last!?"
Have You Told Anyone Else?: Several times - characters confess their suspicions to a family member, friend, or authority figure, who inevitably turns out to be in league with Friend.
Hope Spot: The first two arcs are really two long Hope Spots.
How We Got Here: The first chapter includes a scene during a UN summit in the 21st Century where several people are introduced as having saved humanity. Subverted in that it happens twice during the course of the story, once about a third of the way through and once again towards the end. Also since both times are similar it is hard to tell which one is the one being shown in the first chapter.
Humongous Mecha: Subverted in chapter 41. In the slightly exaggerated words of one hostage robotics expert: "Robots do not work that way!"
Jigsaw Puzzle Plot: When the story alternates between about three or four time periods, includes the liberal use of flashbacks and flashforwards, has a few timeskips, and is told in only rough chronological order, you know you've got one of these.
No Hugging, No Kissing: The closest that Kanna ever gets to a romance is blushing in the last chapter while interacting with Chouno. Likewise Kenji's relationship with Yukiji has never gone anywhere and despite their communication at the end doesn't seem to be going anywhere yet, either.
To be fair, it's probably hard to think of romance with all the saving-the-world shit going on. Actually seems to be Urasawa's trait to not show romantic scenes on-screen.
No Infantile Amnesia: Averted as a constant plot point throughout the story is the cast's imperfect memories of their childhood. Though played straight and Justified in Kanna's case.
Not His Sled: The third film actually made a major selling point out of having a different ending from the manga.
Older and Wiser: Due to the large timeskips in the series, most of the original protagonists become this eventually. Otcho and a few others become this after the first timeskip, and the rest, especiallyKenji become this after the second. This usually comes hand in hand with them taking a level in badass.
Power Walk: Kenji and co. do one in a manner most baddass when they head off to take down Friend's mecha. In fact, the image of them silhoutted against the robot's eyes is one of the most iconic ones in the series, leading to it being duplicated almost perfectly in the movie adaptation.
Psychopathic Manchild: Many of Friend's followers come off as this. The scene where they're arguing over how to build their Humongous Mecha and then later when they're laughing hysterically and cracking jokes about the carnage it causes demonstrate it best.
Friend himself shows shades of this as well. Enacting a doomsday scenario dreamt up by grade schoolers to show up one of the kids who made said doomsday scenario certainly doesn't help his case.
Reality Ensues: The entire scene involving Shikishima and Friend's followers consisted mainly of the former explaining to the latter how the Humongous Mecha seen in anime (when the group was arguing over building one in that style) could never possibly function in real life.
Redemption Equals Death: Many characters trying to redeem themselves, especially the ones that once worked for Friend.
Red Oni, Blue Oni: Kyoko and Kanna. One often acts on impulse rather than deliberation, partaking in the anti-Friend movement almost entirely by mistake. The latter can keep calm during very stressful situations and generally does not show much emotion unless someone makes her really upset.
Simulation Game: A painstakingly detailed representation of 1971, used inside Friend Land and can also be accessed from the Diet building. The heroes use it to find details from Friend's plans in the present and, sometimes, interact with their former children selves.
Shaggy Dog Story: The first two story arcs, in which Friend ultimately realizes his plans despite Kenji/Kanna and pals' best efforts to foil them.
Shut Up, Hannibal!: Kenji does an epic one of these to Moroboshi's killer late in the story, where he calmly makes him completely breakdown when he exposes his Card-Carrying Villain persona as being merely a facade. What makes it more epic is the fact that he's facing down the barrel of a gun the whole time he does it.
Square/Cube Law: Specifically mentioned by Shikishima as the reason Friend's Humongous Mecha can't work the way he desires it to. Then ignored as Shikishima went on to actually create a working version of the robot years later.
Stepford Smiler: Near the end of the manga, it's revealed that many of the Friends have pretty much turned into this, having to keep a sunny disposition at all times for fear of rejection.
Storming the Castle: Happens three times in the final arc: firstly when Kenji and co storm the 'castle' of Moroboshi's killer and twice when the resistance storm Friend's tower. The second time is much easier for them seeing as how all the guards have lost their morale.
Stylistic Suck: Kenji really doesn't enjoy the 169th Friends Concert, even apart from the need to keep an eye out for the Big Bad.
Don't forget Kanna. From taking her first steps to walking into the crossfire of a gang war.
Otcho too. From salaryman to freelance ninja in a couple of years.
The Unreveal: About a dozen characters get to see Friend's real face before the readers ever do.
Neither the readers nor the characters ever see the second Friend's real face at all. They find out his name, though.
Tokyo Is the Center of the Universe: Young Kenji and his friends write a story about supervillains conquering the world. "So what's gonna get hit first?" "Tokyo?" "That's last. The important stuff has to happen in Japan, so if they start here, it'll be all over already." Much later, the story starts coming true.
True Companions: There's only one reason for full-grown level-headed adults to literally put their lives aside and travel back to their hometown, from as far away as Germany in one case, just because of one cryptic note saying 'let's take this symbol back.' In Otcho's case, knowing it was Kenji did it for him.)
Unusually Uninteresting Sight: Nobody really seems to care all that much about gas mask-wearing businessmen carrying suspicious briefcases, especially in the middle of a worldwide outbreak of a mysterious deadly virus.
Wham Episode: There are quite a few throughout the series. Most notably is when Friend is both killed and unmasked, halfway through the series. The chapters surrounding the 2015 World Expo and Kenji's return also qualify.
The final twenty or so chapters are just full of nonstop wham. To be expected with the Grand Finale, really.
The Kenji Faction marches off to the big climactic showdown with Friend. Cue a 15 year Time Skip. Friend won, and now rules the world while Kenji and friends are regarded as history's greatest villains.
Your Princess Is in Another Castle: It initially seems like the series is going to end when the heroes try to stop Friend from destroying Tokyo on Bloody New Year's Eve with a giant robot. However, as you can probably tell from the chapter count, that it is most definitely not the end. It turns out that Friend was just using the (fake) robot so that he could destroy it himself and play the part of the hero, whilst framing Kenji and his friends for all the chaos and destruction. Suddenly, the story jumps forward 15 years and Friend is now head of an opressive Japan, and all our heroes are either scattered, in prison, or presumed dead.Oh Crap.