Six Gates World is a franchise founded by Hitoshi Yasuda and Group SNE, in response to the popularity of Magic : The Gathering. Starting with the release of a novel series, it was later followed by a card game, role playing games, drama cd's, manga series and many more novels. The card game, Monster Collection, became so popular that it hijacked the original franchise title in culture, though the distributors still present Six Gates World as the overarching title.

[[WhatDoYouMeanItsNotForKids While it does feature teens with Mons, do not mistake it for being work safe]]. This franchise predates the Lighter and Softer Mons age that started with Pokemon and so it can feature explicit gore and nudity, though lately it has been working to be more open to a broader audience.

The Six Gates World is a FlatWorld where magic was an active part of evolution. Each corner of the disc is governed by one of the four cardinal elements, while heaven and deep earth belong to the holy and demon elements. The continuity begins with the Magic Kingdom, [[MagiTek which created the summoning system]], which ultimately contributed to its downfall and pummeling the world back into a medieval state. After centuries, the system was rediscovered and considered to be wicked magic, [[BurnTheWitch leading to persecution of anyone practicing it]]. It takes another few centuries before magic becomes standard practice in the world and eventually an accepted part of life, at least, up until the world wide collapse of the system about three thousand years after its creation.

For the [[LighterAndSofter Tengai]] continuity, see MonColleKnights.

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* AfterTheEnd
* AscendedDemon - Raferou
* BigBad
* BlackMagic
* BlessedWithSuck - Summoners who misuse their powers too much gain immortality, but only because they're taking over the physical traits of their abused monsters to the point of being more magic than human. They don't get the powers of the monsters, it is irreversible and they're lucky if they have skin everywhere it ought to be.
* BodyHorror
* ChestBurster
* CorruptChurch
* CrapsackWorld
* Cyberspace, which doubles as SpiritWorld due to MagiTek.
* DarkIsNotEvil
* DragonRider
* ElementalPowers: [[PlayingWithFire Ruby]], [[BlowYouAway Shiljia]], [[MakingASplash Ariaolo]], [[DishingOutDirt Gringul]], [[LightEmUp Lendir]] and [[CastingAShadow Dervis]]. The cardinal four produce four mixture elements.
* FantasticRacism
* FallenAngel
* GreatBigBookOfEverything: The Encyclopedia Verum. Not actually a book, but an organic supercomputer.
* HeelFaceTurn: If a Blackwinged Angel appears and he hasn't already, he will.
* HolyCity: Sazan
* HumansAreSpecial: Only because nobody knows the True Name of the species, which gives them an edge. Humans noticed this and [[TakeOverTheWorld it got to]] [[WellIntentionedExtremist the head of some]].
* LightIsNotGood
* MagicMusic: One type to bring life, another to bring death.
* MedievalStasis: At least, after the end.
* MindControl: What the more vicious summoners do with their Mons. Kinder ones just offer guidance.
* Mons: Depends on having a specific True Name, so even humans can be Mons.
* OrganicTechnology
* OurAngelsAreDifferent
* OurDemonsAreDifferent
* OurDragonsAreDifferent
* OurVampiresAreDifferent
* PainfulTransformation
* Pantheism
* PhysicalGod
* PsychicLink: Not merely a psychic link, a nervous system link. This is already nasty if the mosnter dies when one is linked to it, but even more since the nervous system persists a while after death and something may start eating the critter one is linked to.
* SiblingYinYang: Milk and Silk.
* SlidingScaleOfIdealismVersusCynicism: Despite all the crap that goes on in the world, the heroes tend to be firmly idealistic and noble.
* SnakePeople
* TheBeastMaster
* TheEmpath: Should empathic people become summoners, they might have the benefit of visions and a mild prophetic ability, but the downside is that they lose control of monsters the more pain they experience from them.
* TrueName: Required for a summoning.
* WhiteMagic