'''12 Beast''' is a one-shot by {{Pixiv}} artist Takemaru "Okayado" Inui that became an ongoing manga series.

The one-shot follows the adventures of General Eita Touga, his support staff Aero, and their army of mercenary monsters as they try to save the world of [[AlternateDimension Live-Earth]] from the Gigas, massive machines exterminating the inhabitants, the Autana (the series' term for half-human monsters).

With the might of their incredibly diverse troops, strengths complemented and weaknesses covered; the [[ExactlyWhatItSaysOnTheTin Gigas Slayer,]] a steel gauntlet that gives Eita superhuman strength and allows him to borrow Aero's power; and his PSP, tablet and a war game for any and all strategic planning, they travel across the land defending the weak and slaying the anti-Autana weapons... provided they don't die of starvation first or stage a mutiny, as said army is [[PerpetualPoverty perpetually broke,]] and Eita [[ChronicHeroSyndrome can't resist helping the needy and poor.]]

The ongoing tells the story of how they get there: Eita is a high school ninja gamer from PresentDay Earth who'd like nothing more than to keep out of danger, until Aero, a [[HarpingOnAboutHarpies harpy]] from Live-Earth, shows up to convince him to help protect the Autana, a Gigas hot on her trail.

Eita inadvertantly accepts Aero's request after he trashes the Gigas, and so they set out to save Live-Earth, recruiting their army as they go (including [[SnakePeople Lamiae]], LizardFolk, [[OurCentaursAreDifferent Centaurs]], [[FaunsAndSatyrs Satyrs]], [[ALoadOfBull Minotaurs]], Kobolds, [[{{Mummy}} Mummies]], Dullahan, {{Golem}}s, [[UnscaledMerfolk Scylla]], and [[BlobMonster Slimes]]).

... oh yeah, did we mention the abundance of [[CuteMonsterGirl hot monsters]] and fanservice?

For Okayado's other works, see ''Manga/DailyLifeWithMonsterGirl'' and ''Manga/DeadlineSummonner''.

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!! This work provides examples of:

* AccidentalPervert: Eita attracts dangerous, violent trouble in three ways: being sought after for his heroism and combat prowess, acting on his heroism and combat prowess, or accidentally groping, ogling, and/or offending the various females of both Earth and Live-Earth. Sometimes all three at once.
* TheAce: Heavily implied with Eita's brother, Kouki.
** All but confirmed with the second chapter, really.
* AdamSmithHatesYourGuts: Despite saving Live-Earth from the world-destroying threat of the Gigas, Eita's army STILL needs money to function properly. Food doesn't pay for itself, unfortunately.
* ALoadOfBull: The Minotaurus of the Labyrinth. Stories that Aero and Jawea paint them as savage blood-thirsty monsters, although reality proves this is not the case...
* AloofBigBrother: Eita's brother Kouki left the dojo a year ago. He is the one that sends Aero Eita's way and starts the plot. It's implied that they aren't exactly close.
* AlternateDimension: Live-Earth.
* ArtisticLicenseBiology: The harpies are clearly based more on what would be cool than what would actually work in real life. Especially obvious since the author's other work, ''Manga/DailyLifeWithMonsterGirl'', goes to a great deal of effort to make sure everyone's biology makes sense. Here, harpies have arms, wings coming out of their backs, and the women all have large breasts. ''Manga/DailyLifeWithMonsterGirl'' harpies have arm-wings and apparently pubescent bodies to cut down on weight in order to be able to fly.
* AsskickingEqualsAuthority: In Live-Earth, "biting and clawing your way up the ranks" takes on literal meaning.
* AttackAttackAttack: The Harpies' initial plan to defeat the Gigas was essentially this. [[CurbStompBattle It did not work as well as they thought.]]
* AttentionDeficitOohShiny: Harpies are a curious, highly excitable and very energetic race of Autana that can't really be bothered to--[[SelfDemonstratingArticle wait, was that--? AWESOME!]]
** This is even extended to the entire tribe. Even the elders tend to have bad short-term memories.
* BattleBoomerang: A very large one was used by War Leader Jawea as her weapon-of-choice. She claims that it can slice through metal.
* BizarreSexualDimorphism: Male Minotaurus look like traditional Minotaurs, complete with large size, muscled bodies, and a bovine head. Female Minotaurus, on the other hand, have female human heads and are much more slender. But they are still very large, have hoofed feet, and very, very strong.
* BlackSheep: Aero had the misfortune of seeking sanctuary with the Harpy tribe just before the Gigas attacks started. War Leader Jawea blames it on her black wings. [[note]]Interestingly, in the full-colour cover of the first chapter (not the original one-shot) Aero is shown with blonde hair and dark blue wings, nowhere near black.[[/note]]
* TheBlacksmith: The Smith of the Labyrinth.
* BoobsOfSteel: War Leader Jawea has quite the impressive chest, and the fighting skills to match. [[AuthorityEqualsAsskicking She didn't get that position and title for nothing, after all.]]
** Another example would be Shei the Lizardwoman in the one-shot.
* BoobyTrap
* [[BraidsBeadsandBuckskins Braids, Beads and Buckskins]]: The attire of the Harpies look inspired by Native Americans.
* ChronicHeroSyndrome: Much to the detriment of his army, Eita cannot refuse even a broke tribe in the middle of nowhere. It wouldn't be so bad if this weren't the majority of their jobs, though...
** Aero mentions this is specifically why his brother sent her to him.
* [[CuteMonsterGirl Cute Monster Girls and Boys]]: Unlike his [[Manga/DailyLifeWithMonsterGirl other]] [[Manga/DeadlineSummonner works,]] Okayado delivers for both genders. While the focus is still mostly on the girls, his army does not lack eye candy for other orientations.
* DetachedSleeves: If Aero, for any reason, needs to hide her [[CuteMonsterGirl true]] [[HarpingOnAboutHarpies appearance,]] she can rely on these to hide her talons.
* DirtyOldMan: Eita's grandfather and sensei. His ninja "dummy" would not look out of place in an H-game, and his interest in Eita's PSP is a visual novel--in which he is trying to achieve the "Harem" ending.
** He gets ''very'' excited upon catching Aero's scent--the "scent of a woman."
* DoesThisRemindYouOfAnything: The Gigas in the original one-shot seems ''very'' intent on savouring his meal.
* DungeonCrawling: The Labyrinth is a classic example, filled with treasure and death traps.
* EasternZodiac: The Twelve Divine Generals leading the Gigas invasion are possibly named after the animals in the Zodiac.
* {{Ecchi}}: Less racy than Okayado's better known [[Manga/DailyLifeWithMonsterGirl work]], but is still loaded with fan service.
* EvilCounterpart: [[spoiler: It appears the Gigas' controllers are gamers scoring points by attacking the Autana.]]
* ExactlyWhatItSaysOnTheTin: The Gigas Slayer is one of the few things able to kill a Gigas.
* {{Fangirl}}: Aero's a Ninja fangirl.
* FantasticArousal: Harpy wings are ''extremely'' sensitive to touch and stimulation. [[spoiler:It comes in handy with Eita's fight with the Harpy War Lord.]]
* FishOutOfWater: Eita, who spent much of his time after arriving in Live-Earth curled up in the fetal position and playing his PSP because the shock of being in a new world was too much for him.
* {{Foreshadowing}}: In chapter one's full-colour cover, Eita has Aero and 11 other girls with him, [[{{Badass}} all looking ready for combat.]] How many generals were there, again?
* FunbagAirbag: Asterio the [[ALoadOfBull Minotaurus]] is happy to cushion Eita's fall with her large breasts...
* GagBoobs: Expected to be done whenever there are large chested girls about.
* GenkiGirl: Aero is highly excitable and cheerful. The first thing she does when she arrives at Touga dojo? Examine the weapons and ''geek out.''
** Later it is shown that she has a room in her house dedicated to all the Ninja merchandise she owns. If you haven't guessed it by now, she's ''very'' passionate about things.
* HarpingOnAboutHarpies:
** Aero, Eita's assistant. Not to be confused with Aero of ''Manga/DeadlineSummonner'', who is also a harpy and the protagonist's assistant.
** A large number of them are also present in Eita's army.
** Chapter 2 introduces a large tribe of harpies. Most of the members were refugees from other (destroyed) villages.
* HeadlessHorseman: A female Dullahan shows up riding a centaur.
* HonorBeforeReason: Lampshaded and Subverted. War Leader Jawea claims that the Harpy tribe will fend off the Gigas to protect their clan's honour. Eita advocates running away, to which War Leader Jawea (eventually) replies that doing so will leave over half of their tribe--the young, the elderly, and flightless-- behind.
* HotSpringsEpisode: The setting of the mini-chapter 4.5, with Aero and Jawea bathing while Eita tries his best to hide from the two of them (especially Jawea).
* HumongousMecha: Piloted by the positively adorable golem girls.
** The Gigas are also composed entirely of these. The anti-personnel models are large as a house. The ones made for conquering villages? Well...
* IronButtMonkey: Eita just ''cannot'' catch a break.
* MundaneMadeAwesome: A war game in Eita's PSP and tablet allows him to plan strategies against the Gigas. It translates shockingly well into actual battles.
* NamesTheSame: As Aero the Harpy, from ''Manga/DeadlineSummonner''.
* {{Ninja}}: It's a Touga family tradition.
* TheNudifier: One of the attack of the Gigas is releasing a conductive liquid on a crowd and then coursing some kind of electrical weapon though the afflicted targets. A side affect of the liquid is that is dissolves clothing.
* ObfuscatingStupidity: Eita in spades. In our world he was actually training in ninja arts, though apparently reluctantly. This makes him far more dangerous and skilled then his outward otaku personality might imply. [[UpToEleven Then he got an army to back him up.]]
* OurCentaursAreDifferent: The Centaurs here are similar to ones found in Okayado's [[{{Expy}} other]] [[Manga/DailyLifeWithMonsterGirl two]] [[Manga/DeadlineSummonner works]]. They are more like English knights of a royal court instead of a barbarian horde. They also wear full suits of armor to battle in the one-shot. They also have horse ears instead of human ears.
* PantyShot: Most harpies don't bother with more than underwear.
* PerpetualPoverty: While Eita's army is powerful in their extreme-coordination, making the best of the different species' strengths, and covering their weaknesses, it is not the best funded. It is not helped by Eita's [[ChronicHeroSyndrome compulsion to help anyone and everyone suffering from the Gigas, regardless of their ability to compensate them.]]
* PervertRevengeMode: Like Okayado's other male protagonists, [[Manga/DailyLifeWithMonsterGirl Kimihito Kurusu]] and [[Manga/DeadlineSummonner Mamoru Onodera,]] Eita's [[ThanksForTheMammary hands have an almost magnetic attraction to all the wrong places on a woman's body,]] and the victims do not hesitate to set him straight.
* PowerFist: Eita has a magical gauntlet that gives him super-strength. It also allows him to borrow the powers of his lieutenants for particularly strong attacks, one of the few things that can destroy a Gigas. Appropriately, it is christened the Gigas Slayer.
** Eita brought the original version of the gauntlet from Earth. With the help of his ninja training, it could deflect a projectile ''specifically'' made to destroy the metal it was made out of.
*** However, during his first battle against a full-sized Gigas, it was destroyed. This prompts him to go to the Minotaurus to have it fixed.
** These are also the Golem girls' weapons of choice.
* ThePowerOfFriendship: Eita specifically fights for the sake of saving the Autana and his troops. It's implied that his army stays with and is loyal to him out of a sense of honour and personal debt more than anything else. Which is a '''very''' good thing, considering the army is [[PerpetualPoverty almost always broke.]]
* SchizoTech: Justified and explained, as Autana [[CuteMonsterGirl (Cute Monster Girls/Boys)]] and Ausuna (Real World Humans) have been traveling between worlds for a while, so pieces of technology (i.e. a VHS) will get leaked into Live-Earth.
** {{Magitek}}: Chapter 2 explains that, with the technology exchange that happens time to time, magical versions of real-world items were developed. Examples include the crystal ball television and alchemically-powered generators.
** Chapter 4 reveals that smartphones have made it into Live-Earth, with working reception.
* SnakePeople: Lamiae are another part of Eita's army.
* TheStrategist: Eita plays this role as the general of his army in the One-shot. He also does it again when the Gigas attack the harpies.
* {{Stripperiffic}}: As with Okayado's other works, this is to be expected whenever [[CuteMonsterGirl Cute Monster Girls]] [[GenderInvertedTrope (and Boys!)]] are around. For specific examples:
** Harpy fashion is designed with mobility and flight in mind, keeping materials light and coverage at a minimum.
** The Lizardmen are highly mobile, and thus wear only a few pieces of armour like steel shoulder pads, gauntlets, and boots.
** Lamiae are half-snake, and shockingly fast for their size. If anything, armour is superfluous and clothing just a fashion statement.
** Slimes can't really fit into most conventional clothes, being semi-liquid and naturally slippery.
** Merfolk and Scylla spend the majority of their time underwater; anything larger and more flowing than a bikini will prove problematic when swimming, unless you specifically design it for hydrodynamics.
** Kobolds, like Lamiae and Harpies, are a more feral breed of Autana, and use their speed and strength beside, requiring maximum mobility. What little items they don are to look more menacing.
** Minotaurs are walking tanks. Armour is kept to a minimum, and they enjoy the freedom.
** It would be problematic for Mummies to keep re-wrapping themselves, magically or not. When their bandages come undone, most just choose to keep it that way.
* ThanksForTheMammary: See PervertRevengeMode above.
* TrappedInAnotherWorld: While there is a way to get back to Earth, Aero mentioned that it would take a large amount of magical power to do so and a large amount of time to gather said power. In short, Eita's stuck until he finishes his quest.
* WhoWearsShortShorts: A lot of Harpies do! Appropriately enough, their style mimics ''Manga/DeadlineSummonner'''s Aero's shorts, said manga being another of Okayado's works. Though, they aren't "short shorts" so much as they're [[PantyShot underwear]].
* [[WhyDidItHaveToBeSnakes Why Did It Have To Be Darkness]]: Harpies in general do not like the dark, and would freak out if someone turns out the lights.
* YoureDrinkingBreastmilk: Subverted. The female Minotaurus have a tendency of serving their guests raw milk. While it is implied that they made it, judging from the dialogue, the focus on their very large breats, and the other characters' [[{{Squick}} reactions]], a cutaway to a picture of cows show that they milked the cows instead.