Parallel World

refers to divergent timelines that advance in adjacence to one another. In Fate/EXTELLA, it is stated that a World qualifies for culling if it entirely lacks the potential to diverge into Parallel Worlds.
Incidentally, Archimedes' capacity to travel between Parallel Worlds is referred to as .
==Characteristics==
The primary history of the worlds is called the , consisting of all worlds that have not been pruned. Worlds that have been cut off from Proper Human History in this way are known as , discarded even from Parallel World Theory.Fate/Grand Order: Cosmos in the Lostbelt - PrologueFate/Grand Order: Cosmos in the Lostbeltlt: 黄金樹海紀行 PV
Although most works share a similar foundation and could be said to all be Parallel Worlds to each other, there are actually two major branches of worldlines, the and the . Fate Worlds are based in the "Affirmation of Human History" where Heroic Spirits can be summoned as Servants, and Tsukihime Worlds are based in the "■■■■■■■■ of Human History" where the concept of summoning Heroic Spirits is laughable and where Dead Apostles, the antithesis of Human History, stand at the center of the story. There are also worlds that share elements of both Fate and Tsukihime worlds, but do not clearly favor one side or the other.The BAMBOO BROOM DIARY - 2017/4/15: Nobunobuno, nobunonobunobu.
Parallel Worlds are normally accessible to others only through the Second Magic. In the computerized setting of Fate/EXTELLA, Archimedes and Dark Eliza are able to Slide between worlds by way of a System Administrator privilege granted by SE.RA.PH. Meanwhile, Miyamoto Musashi has an unusual condition in which she involuntarily "jumps" between worlds at random. Other, more exotic means of traveling between Parallel Worlds such as Rayshifting and the Zero Sail also exist, and the Moon Cell seems to have at least a limited ability to deploy its agents to Parallel Worlds if necessary, as in the case of BB traveling to the Grand Order world. However, these alternative means are far more limited in the number of Parallel Worlds they can access and require special protocols to be performed safely. Characters of many different settings can interact and gather in Ahnenerbe.
*The stories of Kara no Kyoukai and Tsukihime were originally considered both to be small happenings in the same world. Afterward, due to slight differences in the ages of certain people and differences in the makeup of certain families, they can be thought of as subtly shifted Parallel Worlds. 
*The world of Notes takes place in an undetermined future where the world dies while humans continue to live on its body, and its current state involves Crimson Moon.
Fate Works Timeline.jpg|Timeline of the various Fate spinoffs from TYPE-MOON Ace Volume 15.
Fate Works Relations.jpg|Relationships between the various Fate spinoffs from TYPE-MOON Ace Volume 15.
*Worlds connected to Fate/stay night:
**Fate/Zero is presented as a prequel to stay night, but is actually a subtly different Parallel World per TYPE-MOON Ace Vol. 10.
** Lord El-Melloi II Case Files takes place in the same world as stay night, although it has a greater focus on Magecraft and a different "atmospheric density" due to the influence of the author, Makoto Sanda.Fate/strange Fake Volume 1 - Afterword: Nasu Kinoko's Commentary The Adventures of Lord El-Melloi II is set several years after Case Files and a version of stay night combining elements of all three routes.The Adventures of Lord El-Melloi II Volume 1: The Man Who Devoured God - Afterword For example, Shirou Emiya has followed Rin Tohsaka to London, as in the Unlimited Blade Works route, but Rin claims they are not dating, as in the Fate route. It is also set several years before Kara no Kyoukai: Future Gospel.Makoto Sanda Twitter 10:16 PM JST · Aug 13, 2021
** While Fate/school life shares some similarities with Lord El-Melloi II Case Files, they are different world lines.Eiichirou Mashin Twitter 1:53 PM JST · Apr 21, 2018
** The world of Fate/strange Fake is a future possibility, called by Kischur Zelretch Schweinorg a (or perhaps the opposite)Fate/strange Fake Volume 1 - Extra Chapter: Observer. Or, Character Creation translation, p.187-193 that is somehow completely different despite having the same terms and reaching the same conclusion as Fate/stay night. This world is derived from the timeline of Fate/school life, with strange Fake being closely linked with its history (though it will not go into detail on its version of the Fifth Holy Grail War).Flat Escardos's Darts Trip of Himuro no Tenchi Appreciation: A Preview - Afterword Despite nominally being a Fate world, it has many elements of a Tsukihime world.
** The world of Fate/Grand Order is a closely related parallel world where 2004 saw the first and only Fuyuki Holy Grail War, instead of the Fifth as in stay night. The war was won by Marisbury Animusphere, who used his wish to gain the resources to found Chaldea Security Organization and activate CHALDEAS.
** The world of Fate/Requiem was the same as the World of Fate/stay night until the Fifth Fuyuki Holy Grail War. 30 Grail Wars were held simultaneously across the globe, creating mass chaos that would snowball into World War III. The eventual winning Master of the conflict, Chitose Manazuru, used her wish to radically change the world.TYPE-MOON BOOKS material
* The Tsukihime Remake and Mahou Tsukai no Yoru take place in the same parallel world. Clock Tower 2015 shares this world as well, although it concerns themes most closely associated with the World of Fate/Grand Order.
*The world of Fate/type Redline is not directly connected to any other Fate works other than its antecedent gag series, Fate/KOHA-ACE.Keikenchi Twitter 2:16 PM JST · Dec 10, 2019 In this world, the Holy Grail Wars were conducted in the Imperial Capital Tokyo of the Empire of Japan in concurrence with World War II. The Third Holy Grail WarFate/type Redline - Chapter 11.2 occured in Shōwa 18 (1943 A.D.), and abruptly ended with the Grail and Servants vanishing.Fate/type Redline - Chapter 2.1 A later Holy Grail War held in Shōwa 20 (1945 A.D.) ended with an enormous explosion in the Imperial Capital, killing 200,000 and leaving enormous craters that permanently altered the coastline.Fate/type Redline - Chapter 13.1 The of Japan persists into the 2020s.Fate/type Redline - Chapter 11.1
===Fate/stay night Universe===
The three routes of Fate/stay night can be called Adjacent Worlds existing at the same time in some sense. When asked how the routes would appear to Zelretch, Kinoko Nasu stated that Zelretch observing the routes as parallel would make it "true", and that Nasu would prefer that only one route existed instead.
*Fate (route)
*Unlimited Blade Works (route)
*Heaven's Feel (route)
===Fate/kaleid liner PRISMA☆ILLYA Universe===
Fate/kaleid liner PRISMA☆ILLYA has portrayed two existing worlds: the main setting, the "World of Illya"; and the parallel "World of Miyu".
*The "World of Illya" has a similar history to Fate/stay night and Fate/Zero, but instead the Fuyuki Grail system is dismantled before the Fourth Holy Grail War can begin. Illya lives as a normal girl until encountering people and Magecraft from the World of Miyu.
*The "World of Miyu" is different to the "World of Illya".
**Pandora hasn't opened Pandora's Box, thus her legend isn't well-known to the people.Fate/kaleid liner PRISMA☆ILLYA 3rei!! - Chapter 44: "The Problematic Truth"
**The Ainsworth Holy Grail War operates on a Class Card system and was founded by the Ainsworth, Matou and an unknown family.
**The World has experienced a shift in the axis of the worldFate/kaleid liner PRISMA☆ILLYA 3rei!! - Chapter 17: "The Foreseen Eternity" and the start of the depletion of its Magical Energy.Fate/kaleid liner PRISMA☆ILLYA 3rei!! - Chapter 18: "The Penultimate Truth" The world is similar to Notes.
===Apocrypha Universe===
The world of Fate/Apocrypha is a Parallel World to Fate/stay night where the timeline differs during the Third Holy Grail War. Apocrypha is a world that was the same up to a point, but which is now completely different.
*The Einzbern summoned a Ruler-Class Servant instead of an Avenger-Class.Fate/Apocrypha Volume 3: Triumphal Return of the Saint - Prologue
*The Greater Grail was removed from Fuyuki after the Third Holy Grail War and disappeared for many years.Fate/Apocrypha Volume 1: Apocrypha: Great Holy Grail War - Chapter 1
*Darnic Prestone Yggdmillennia spreads information about the Fuyuki ritual throughout the Magi community, resulting in Subcategory Holy Grail Wars erupting on every continent.
===Moon Cell Holy Grail War Universe===
The world of the Moon Cell Holy Grail War shares an identical history with Fate/stay night up until a "certain major incident" in the 1970s causes the World's Mana to steadily decline until it completely disappears by the 2030s.Fate/EXTRA Visual Fanbook - Page 079
*The "EXTRA" universe is where Fate/EXTRA takes place.
**Rin Route.
**Rani Route.
*The "CCC" universe is where Fate/EXTRA CCC takes place.
**Archer Route.
**Caster Route.
**Gilgamesh Route.
**Saber Route.
**Sakura Route.
*Fate/EXTRA CCC Fox Tail
*Fate/EXTELLA
===Tsuki no Sango Universe===
The world of Tsuki no Sango takes place in approximately the year 3000, when humankind arrived at the peak of its civilization, but is losing its will to keep living.
*It is a world in which the events of Tsukihime didn't take place.
*Unlike the world of "EXTRA", Tsuki no Sango is a degenerated world where Magecraft yet lingers.
==Development==
Fate/stay night was originally imagined to be set in the same world as Tsukihime before it was decided to split them.
==References==
it:Mondo parallelo
vi:Thế Giới Song Song
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Category:Terminology in Kara no Kyoukai
Category:Terminology in Tsukihime
Category:Terminology in Tsukihime Remake
Category:Magecraft terminology
Category:Terminology in Fate
Category:Second Magic
Category:Cosmology