[[quoteright:276:http://static.tvtropes.org/pmwiki/pub/images/btx-intro_5924.jpg]]
[[caption-width-right:275: [[Manga/SaintSeiya PEGASUS RYUSE-errr, I mean, MESSIAH FIST!]]]]
Written by MasamiKurumada after he was forced to finish ''Manga/SaintSeiya'' prematurely due to the [[ExecutiveMeddling insistence of his publishers]], ''B[='=]t X'' has a similar premise but with a different setting and execution. Some people consider this as ''Saint Seiya [-[[RecycledINSPACE WITH SCIENCE!!!]]-]''

The story begins with Teppei Takamiya, as he travels to China after years of living quietly in the fictional Kamui Island. He attempts to reunite with his brother Kotaro, who left Germany five years ago to study robotics at a university. Unfortunately, no sooner than his brother begins an exhibition about an advanced form of machine, he's kidnapped by a HumongousMecha in the shape of a wasp and a servant of [[TheEmpire the Machine Empire]]. Teppei starts a chase, using a gauntlet known as the "Messiah Fist" to hold onto the wasp as it travels to a secretive base in the Gobi Desert which serves as the Empire's headquarters.

Getting thrown into a garbage heap and facing a cyborg he somehow is familiar with, Teppei's blood awakens a relic from the past; a kirin-type B't known only as "[[OneLetterName X]]" which, five years ago, was considered the most powerful B't in existence. Both are equally stubborn, although quite different in many ways, and after a few initial squabbles, X resolves to help Teppei in his quest to save his brother.

Along the way, we find out quite a bit about Teppei's past, the reasons Kotaro was kidnapped, and the Machine Empire's plans involving a home-grown monster of [[Anime/MobileFighterGGundam Devil Gundam]] proportions.

Both the manga and the anime have been licensed in America.

As of June 2013, they have revived into a [[http://www.youtube.com/watch?v=-NPY7sz2WqM PACHINKO]] [[https://www.youtube.com/watch?v=b4kKPF0Lr7A GAME]]!!

The character sheet is located [[Characters/BtX here]], and it seriously needs more love.

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!!This series provides examples of:
* ActionGirl: Teppei's teacher Karen, who had been one of the Empire's Four Knights up until five years ago. Aramis is another example.
* AirJousting: A lot of fights take place in the air.
* ArmorIsUseless: averted for the most part. Foh, Hokuto, and Ron rarely use theirs simply because they either hate fighting (Foh and Hokuto's reason) or they're just that good. (Ron's reason)
* BatmanCanBreatheInSpace: Applies to everyone with a B't. Except for instances involving the B'ts' WeaksauceWeakness (see below), a B't's protective "Guard System" enables it and its rider to withstand anything ranging from magma to the void of space.
* [[ABoyAndHisX A Boy And His Kirin]]
* CallingYourAttacks: All the time.
* [[spoiler: CameBackStrong: BT'X and Teppei after the former was reduced to scrap and the latter utterly damaged.]]
* CastFullOfPrettyBoys: It ''was'' made by Kurumada, after all. Also total MrFanservice.
* ChekhovsGun: [[spoiler:Foh's bible and Raphaello's cell]].
* [[CreepyChild Creepy Children]]: Misha and Nasha.
* CyberneticsEatYourSoul: Made apparent with the cyborg named ''Metalface'', who considers sacrificing his own flesh and blood for an immortal robotic body to be an obvious choice.
* DarkIsNotEvil: Karen creates a black version of X, Shadow X, that is just as powerful, a girl, and ''good.''
* DarkerAndEdgier: The Seven Demon Generals Arc and onward.
* DeadpanSnarker: At least in the Tokyopop manga, the ''narrator'' pulls this off in the recap of the previous volume, complete with LampshadeHanging various issues such as Teppei's VitriolicBestBuds status he eventually gets with Foh and company, [[spoiler: the fact that Juggler's real face looks just like a clown face anyways]], etc.
* DefectorFromDecadence: Karen and the other guardians after learning the [[AssimilationPlot true intentions of the Machine Empire]].
* DefeatMeansFriendship: Averted. Teppei never actually defeats Foh in a fight and the best he does against Ron is fight him to a draw. he also never duels either Karen or Hokuto. However, they all eventually side with him.
* DubNameChange: Teppei is named Marlon, Foh is changed to Falcon, Hokuto to Homer, Karen is named Lourdes and so ford. The only ones that remain somewhat the same are Kaos and Metal Face.
* EldritchAbomination: Raphaello in every sense of the word. For a good part of the series, the Empire has to move heaven and hell to keep it under control. And they fail miserably at it.
* EveryScarHasAStory: Teppei and the Four Generals all have physical scars on their bodies and was shown in the OVA. But it's origins were only mentioned in the manga.
** Teppei's scar is an "[[XMarksTheHero X]]" on his forehead, and said it was a "minor injury" from training.
** Karen's scar is a big "X" on her back, though she claimed to Teppei that it was a "minor injury" she gained from old battles, [[RuggedScar readers never really knew the story behind it]].
** Foh's scar is a big "cross" on his back, but like Karen, it's a RuggedScar.
** Ron's scar is a "Lightning Bolt" on his chest, the scar came from Aramis, who defeated him using her sword one time when they were little.
** And Hokuto takes the cake of having the most lengthy story behind his scar, a "Big Dipper" located on his back. This was from a radioactive explosion he encountered when he was little.
* [[MonsterOfTheWeek Enemy Of The Week]]: more a case of two or more weeks.
* {{Expy}}: Pretty much everything in this series can be tracked down to SaintSeiya:
** Teppei looks very much like an older Seiya.
** Ron looks a lot like Shiryu. This, however, doesn't apply to his personality.
** Foh also looks a lot like Hyoga. Then again, it doesn't apply to his personality as well. He can also be seen as the unholy child of Saga and Shaka, with a dash of Lyra Orpheus thrown in. With Shion's hair.
** Adding to the "Huh" factor of the look-alikes, Kotaro looks an awful lot like Shun, if he grew up and cut his hair real short.
** Hokuto is pretty much like Mu with Shaka's aloof personality.
** Karen is basically Aioros, since both are labeled as traitors despite having the best intentions and have a great deal of an impact on the main characters.
** And last, but not least, the B'ts and Battle Gears. Subverted in that they don't split-up to form an armor for their owner.
* FacelessMooks: the regular soldiers from the Machine Empire.
* {{Filler}}: three episodes dealing with the Dark Knights (while in the manga they were defeated all together and very anticlimactically), along with encountering an old member of the Four Knights and also a reclusive scientist.
* FillerVillain: Chaos and the three Dark Knights. Chaos plays an important role, however, coining the phrase "Buddy", which is used a lot in the remainder of the series, and furthering Teppei's CharacterDevelopment. The Dark Knights serve to {{foreshadow|ing}} Teppei's connection with the Sun, and the potential he has.
* TheFourGods: The B'ts used by the Four Generals, replacing Byakko with a Kirin.
* FourIsDeath: Subverted. The Four Knights are, naturally, four in number, and they all eventually resolve to help Teppei. The seven Demon Knights, however, are all out for his blood.
* GratuitousEnglish: "''X! Omae wa ore no [[RobotBuddy baadii]] da!''"
* GeckoEnding: [[spoiler: The world is saved, and very well...[[BittersweetEnding the main cast, not so much]]]] ...[[OvertookTheManga In the anime that is]].
* HackYourEnemy: Hokuto and Demon General Dr. Poe throws [[ComputerVirus viruses]] at each other's B'ts in the manga. Kotaro on the other hand, hacks a laser-beam surveillance camera to aid Teppei to combat the hallways in the anime.
* HeelFaceTurn: ''Plenty'', especially when people realize how dangerous Raphaello really is.
* TheHerosJourney
* HeroicSacrifice: Again, lots of people. [[spoiler: Metalface managed to pull it off twice. Once sacrificing a means of safely travelling a minefield to help out a young Karen years ago which caused him to require his cyborg parts, and once again to secure the force that would destroy Raphaello at the cost of his body]]
* HeroicSpirit: Be it either facing the DespairEventHorizon of B't Rafaello [[spoiler: growing to the giant dark blob ball about to absorb the Earth in the anime or becoming the Ultimate B't in the manga]], it takes the Four Generals plus Kotaro's spirit to give Teppei the power defeat it.
* HighHeelFaceTurn: A noticeable aspect in this series. Pretty much ''every'' female character who serves in the Machine Empire, such as Salome, Karen, and Nasha, will end up having the brains to help Teppei by the end. [[spoiler:Too bad that ''all'' of them die in at least one version of the story with the sole exception of Karin.]]
* HotBlooded: This ''is'' a [[SignatureStyle Kurumada manga]] we're talking here.
* [[HyperspaceMallet Hyperspace Armor]]: The fighters summon their armor out of thin air.
* KillEmAll: [[spoiler: the manga kills off a ''lot'' of people, and in the end pretty much the only two protagonists, both human and B't, that survive are Teppei and Kotaro. In the anime, the last scenes implies that everybody died, including Teppei and Kotaro]].
* MeaningfulName: "B't" is pronounced like "beat", as in "heartbeat". Appropriate considering blood is required to activate one. Raidou, Ron's B't, and Je T'aime, Foh's B't, are other instances.
** BlindIdiotTranslation: In the Spanish localization, however, B't was turned into ''Beta'', deleting any meaning of the original name.
* AMechByAnyOtherName: In this case, a B't.
* MechaMooks: The Ryukans, which are piloted by generic soldiers.
* MidSeasonUpgrade: [[spoiler:After X dies for the first time, Hokuto repairs him. Among other things, Teppei's armor changes and he gets a new attack.]]
** Metalface and B't Madonna gets one as well.
* MyCountryRightorWrong: Deconstructed with the remaining guardians after Karen's supposed betrayal.
* NuclearWeaponsTaboo: Averted. Hokuto's radiation sickness was triggered by being just outside the direct killzone of a nuke that destroyed his home and family and he's got the burns on his back to prove it. [[spoiler: Aramis also tries to kill Raphaello by loading Rosemary up with every nuclear warhead she can find and performing a HeroicSacrifice, but Raphaello's power makes it a SenselessSacrifice.]]
* {{OVA}}: B't X Neo, also known as episodes 26-39.
* OvertookTheManga: The anime entirely skips the last four Demon Knight battles and revamps the final battle against Raphaello.
* PhlebotinumRebel: The Titular B't X.
** [[spoiler: The Messiah Fist]] as well, at least in the anime. [[spoiler:Turns out it was reverse-engineered from a sample of Raphaello's cells]].
* ThePowerOfTheSun: Teppei's awakened power, and becomes the key person in [[spoiler: defeating Raphaello]].
* PoweredArmor: The Battle Gear, in which was focused on Teppei as his TransformationSequence. Anyone with a B't will have the Battle Gear System installed within the B't to be triggered once the command: "''[[ByThePowerOfGrayskull Battle Gear, ON!]]''" is spoken by their Donors in order for them to be applied onto the Donor. The Four Spirit Generals all have wore them in the manga, but only Teppei and Karen wears them in the anime.
* PunctuationShaker: Played straight with "B't", but justified with Je T'aime, which is French for "I love you."
* RedemptionEqualsDeath: Many, many people, especially in the manga. [[spoiler: Juggler, Marcello, Amigo, and Aramis just to name a few. Misha and Nasha also die in the anime after each makes a HeelFaceTurn.]]
* RedOniBlueOni: Teppei and X fit this dynamic quite well, and it's taken to almost VitriolicBestBuds-level proportions.
* RescueArc: Essentially the entire series.
* RoleReprisal: It's pretty clear that Creator/NobuyukiHiyama, Creator/KeijiFujiwara, and most of the main cast came back in the [[https://www.youtube.com/watch?v=b4kKPF0Lr7A pachinko]] for their respective roles. But unfortunately Creator/MegumiOgata (Karen) and Creator/KenyuHoriuchi (Metal Face) failed to come back for their roles.
* [[spoiler: [[HesBack She's Back]]: Karen, now sporting a [[DarkIsNotEvil Black]] [[ActionGirl female version of BT' X]]]].
* ShipTease: [[CyberneticsEatYourSoul Metal Face]] implies Karen had feelings for Foh, though he immediately rebuffs this.
** It has also implied that [[spoiler: Metalface cares about Karen]] [[{{Tsundere}} more than he admits himself to be]].
** [[spoiler: Ron and Aramis]] have this in the manga.
* ShoutOut: From subtle character designs, to the story plot, having The Takamiya Brothers going against the Machine Empire can be seen as a huge take from ''Anime/GodMars''.
* SiblingTeam: The Takamiya Brothers. In the OVA, while Teppei's busy taking out killer-robots by hand in the hallway of the Empire Tower, Kotaro remains inside an office of the tower hacking the Empire database AND help Teppei [[HackYourEnemy take out laser-beam surveillance cameras]] [[DepartmentOfRedundancyDepartment using a laser-beam surveillance camera]].
** SensitiveGuyAndManlyMan: On the appearance, Kotaro is the sensitive guy while Teppei's the manly man; but on the inside, Kotaro's the manly man while Teppei's actually the sensitive one.
* SignatureStyle: The inclusion of a kirin. In many of Kurumada's other works, a kirin (or occasionally a pegasus) has something to do with the protagonist.
* SpellMyNameWithAnS:
** Is it Ron, Lon, or Long?
** And Foh, Fou, or Phoue?
* SuperRobot: The B't.
* ThirdLineSomeWaiting: You have a number of plots going on at the same time. The three big ones are:
** Teppei's RescueArc
** Foh and the other members of the Four Knights trying to determine if Raphaello is indeed an evil that has to be put down and if they should help Teppei.
** Kotaro's Adventures in [[strike: Wonderland]] Underhell where he tries to [[DoingResearch figure out Raphaello's weaknesses]].
* UtopiaJustifiesTheMeans: The Machine Empire's subordinates believe they are fighting to bring about an end to war. Some of them are more dogged in this belief than others.
* ViewersAreGeniuses: Hokuto vs. Dr. Poe... plus any time Kotaro is writing formulas.
* [[WeCanRebuildHim We Can Rebuild Your BT]]
* WeaksauceWeakness: B'ts are vulnerable to certain sound frequencies that damage fragile parts of their systems.
* WhatMeasureIsANonCute: [[PetMonstrosity B'ts, with their design based from a huge range of animal and mythological creature selections]] tend to suffer from this issue pretty seriously. [[spoiler: [[TheIngenue Poor]] [[EverythingsBetterwithDinosaurs Madonna]]]]...
* WhatMeasureIsANonHuman: Teppei initially views X as a tool to help him rescue Kotaro. It takes a while for him to realize X has his own thoughts and feelings. This also applies to Metalface, although his realization came too late.
* WhatMeasureIsAMook: The juggler uses mooks as PeoplePuppets, to which Teppei is horrified ''despite'' having killed hundreds of them by that point. Interestingly, once he manages end his VillainOverride of them, their [[FacelessGoons helmets]] harmlessly blow up and reveal their faces.
* YouFailLogicForever: Deliberately invoked by Hokuto at one point to distract an enemy.
* YouHaveOutlivedYourUsefulness: Aramis is eventually demoted due to her efforts to suppress Raphaello's growth. MonsterClown Juggler takes over for her
* YouWillBeAssimilated: Raphaello's shtick. It provides gallons of terror.
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