Parallel Worlds (並行世界, Heikō Sekai?, also "Adjacent Worlds") 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.[1][2]

Incidentally, Archimedes' capacity to travel between Parallel Worlds is referred to as Sliding (並行移動(スライド), Heikō Idō(Suraido)?).


The primary history of the worlds is called the Proper Human History (汎人類史, Han-jinrui Shi?, also called Pan-Human History), 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 Lostbelts (異聞帯(ロストベルト), Ibuntai(Rosutoberuto)?, lit. "Belt of Strange Tales"), discarded even from Parallel World Theory.[3][4]

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 Fate Worlds (Fate世界, Feito Sekai?) and the Tsukihime Worlds (月姫世界, Tsukihime Sekai?). 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.[5]

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.[6] 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.[7]
  • 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/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.[22]

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".

Apocrypha Universe[]

Main article: World of Fate/Apocrypha

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.[8]

Moon Cell Holy Grail War Universe[]

Main article: World of Fate/EX

World lines of the Fate/EXTRA series

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.[29]

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.[30]
  • Unlike the world of "EXTRA", Tsuki no Sango is a degenerated world where Magecraft yet lingers.[30]


Fate/stay night was originally imagined to be set in the same world as Tsukihime before it was decided to split them.[31]


  1. [v] Fate/EXTELLA - Chapter Altera - Prologue

    Upon the Earth, there is exists the hypothesis of "Adjacent Worlds."

    The World is not one; rather, like a reflection in a pair of opposing mirrors, it infinitely unfolds. Consequently, there cannot exist only a single future -- or so it's thought. In other words --

    Let's explain it like this. The you that exists right now can be described as a you that exists somewhere within this flow of time.

    It's probably difficult for you to envision. After all, it's impossible for humans to even perceive "the Boundaries Between Worlds" (世界の壁, Sekai no Kabe?) -- much less what lies beyond.

    So, how about I rephrase? Worlds that run adjacent are essentially as "possibilities."

    Conclusions that may be possible.
    Bonds that were abandoned.
    Options that went unnoticed.

    Divergent futures, wherein "what ifs" such as these were permitted. It is indeed these "realities in which the future was altered" that are referred to as Adjacent Worlds.

    The you who is now alive --
    By the actions of the you who exists here and now, the course of the World can shift in any number of ways.

    This is proof that "possibility" (可能性, kanōsei?) is itself still alive; positive evidence that your World still lies upon its "proper axis" (正しい軸, Tadashii Jiku?).

    In converse: For those Worlds wherein the act of choice can no longer impact the future, Parallel Worlds cannot exist.

    Such timelines merely advance.
    Losing even the possibility of undoing the past, they become distinct, solitary Worlds.

    Their manifestation is a necessary evil, structurally mandated.

    In those worlds where choiceless choices incessantly persist, the form of the "World" familiar to you cannot endure.

    There should exist worlds ruined by the repetition of choices in mortal error, yes?
    There should exist worlds that excessively advanced their civilization by way of continuous innovation, yes?

    But once a World arrives at such a state, it can no longer be counted as "a World comparable to the others" (他と同じ世界, hoka to onaji sekai?). If the Foundation of a World (世界の基盤, Sekai no Kiban?) has deviated, it becomes that which is known as an Otherworld (別世界, Betsu-Sekai?, lit. "distinct reality").

    But why do such realities become solitary? Shouldn't it be that whatever the future, the possibility of adjacent advancement persists?

    Unfortunately, this isn't the case. The energy to account for the proliferation of unnecessary worlds, exists nowhere within this Dimension (次元, Jigen?).

    That is to say, the ceaseless proliferation of Parallel Worlds may eventually exceed the capacity of the Dimension as a whole.

    Parallel Worlds are a necessary existence, but they cannot be let to freely multiply.

    It's a very rough estimation, but should the Earth persist at its present level of civilization for another century, it's likely that the Solar System will collapse.

    However, the reality is that we live and multiply. The Solar System hasn't yet dissolved (緩和, kanwa?, lit. "loosen" / "relax" / "alleviate") before the sheer volume of data that we produce, and it's likely that the status quo (今の方式, ima no houshiki?, lit. "the present formulation / system") can be sustained for another hundred million years.

    And the principle behind it is simple. To a certain extent, the existence known as the World (世界という者, Sekai to Iu Mono?, lit. "the thing called the World") conducts a heuristic analysis (統計, tōkei?) of timeline survivability (進むと可能性, susumu to kanōsei?, lit. "prospects and potential"), preserving only those Outcomes wherein "the operation of the subsequent era" (次の時代の運営, Tsugi no Jidai no Unei?) isn't impossible.

    For those Parallel Worlds judged to be unnecessary -- the future is closed.

    In more concrete terms, cumulative audits (集計, Shukei?) are conducted at intervals of a century in scale (百年単位, hyakunen tan'i?, lit. "units of a century"), to the end of identifying and preserving only the possibilities (可能性, kanōsei?) of those Worlds capable of guaranteeing "the preservation of capacity for advancement in yet a subsequent century, at bare minimum."

    Per the systematic demands (法則, hōsoku?, lit. "laws") that facilitate the Conservation of Mass (質量保存, Shitsuryō Hozon?), this process could be termed the Conservation of Phenomena (事象保存, Jijō Hozon?).

    Thusly, the civilizations of the many extant Parallel Worlds largely refrain from divergence. You can imagine it as a great tree. The worlds permitted to advance are restricted to the center -- comprising the trunk. Those branches that diverge grow and multiply, but eventually succumb to their limitations (限界, genkai?), falling to ruin without reaching a future.

    You understand, yes?

    Those worlds that advance too far into ruin or prosperity are bankrupt of Parallel Worlds(Branching Potential) (平行世界(かのうせい), heikō sekai(kanōsei)?). Otherworlds (異世界, Isekai?) such as these are little more than blind alleys(dead routes) (袋小路(デッドルート), fukurō-kōji(deddo rūto)?) whose outcomes are foreordained.

    The time of the culling brings a termination to unnecessary possibilities -- the point at which, by force of Observation (観測, Kansoku?), the mutable Histories of the past solidify as a static course.

    This is what the Magi of the Old World (旧世界, Kyūsekai?) referred to as Phenomenon Anchoring Bands (事象固定帯, Jijō Kotei-tai?) -- the Foundations of the Rationalities of Man (人理定礎, Jinri Teiso?).


  2. [v] Fate/EXTELLA - Chapter Altera (Localization) - Prologue

    "Earth scientists have hypothesized the so-called 'parallel worlds,' other versions of Earth and its surroundings, expanding indefinitely like mirrored reflections. If true, that would mean that Earth has not only one future, but many. In other words ..."

    "Think of it like this. The 'you' that you are aware of exists somewhere upon this timeline."

    "It might sound unreal. Humans aren't equipped to perceive, let alone traverse, the 'wall between worlds.' But what if I put it another way? Think of these parallel worlds as other possibilities."

    "Imagine what might have been in your life. Think of the connections that were cut off and thrown away. Options you see now, in retrospect, that you would never have considered at the time. Picture how your life today might be different had those 'what ifs' come to pass. All those variant futures, in everyone's lives, make up the vast array of parallel worlds."

    "Your actions, those of the 'you' in this present moment on this particular timeline, can change the world in any number of ways. That proves such possibilities are alive, and that your world exists on the 'proper axis.'"

    "Conversely, a world where the future cannot be changed, regardless of your choices, can have no parallel worlds. Such a world is nothing but a dead end, solitary and singular, with a past as immutable as its future."

    "This is a necessary evil, a byproduct of the way parallel worlds are structured together. After all, a world where humanity made radically different choices would bear very little resemblance to the world you know."

    "Some worlds may have crumbled by making all the worse choices. Others may have made all the right ones, and rocketed ahead, perhaps too far ahead. In either case, that world can no longer be said to resemble ours, and once a world moves out of sync, it is no longer 'parallel.'"

    "'Why would those worlds become solitary,' you ask? 'Could the people in those worlds not still make different choices?'"

    "Unfortunately, no. This dimension contains a finite amount of energy, and has none to spare for creating new worlds from the worlds gone so far astray."

    "If parallel worlds continued to increase in this manner, their number would eventually exceed the capacity of this dimension. Parallel worlds must exist, but in a manageable quantity. By my own rough calculations, and judging by the civilization of Earth alone, this solar system would collapse within 100 years if parallel worlds expanded without limits."

    "Seeing as how we do, in fact, live and multiply, the solar system is clearly not oversaturated with possibilities at this time, I extrapolate that this dimension can sustain our existence for the next 100,000,000 years."

    "The system works thusly: At regular intervals, the dimension takes stock of the possibilities it contains, and only allows certain outcomes, those that would not cause undue difficulty in managing the next generation, to remain. As for the unneeded parallel worlds, the system closes off their futures."

    "Specifically, every 100 years, it calculates how many worlds will last another 100 years, and supports those worlds only. Have you heard of the Law of Conservation of Mass? This could be called the Law of Conservation of Events."

    "And so, the civilization in these numerous parallel worlds line up with one another. Think of it all as a giant tree. Only the trunk at the center can grow tall. The branches may bear fruit, but eventually they reach their limit, and fall without reaching the future."

    "You understand, yes? There are no parallel worlds for a world that has evolved too fast or crumbled too quickly. Such worlds are merely dead ends whose outcomes are predetermined."

    "And so, there is a set time frame in which these branches are trimmed, extra possibilities are removed, and future histories, once fluid, turn to stone. The mages of the old world called this time frame 'the Foundation of Humanity.'"

  3. Fate/Grand Order: Cosmos in the Lostbelt - Prologue
  4. Fate/Grand Order: Cosmos in the Lostbeltlt: 黄金樹海紀行 PV
  5. The BAMBOO BROOM DIARY - 2017/4/15: Nobunobuno, nobunonobunobu.
  6. Staff Roundtable - The Second Night

    Speaking of Tohno, did you ever think of doing a crossover with 「Kara no Kyoukai」?

    Nasu: No, even though the word rules (special powers/magic) are the same. They're both just small happenings in a single world. That's why the first main character I made is Aoko-san.

  7. [v] December of 2001

    It's the first post on the spoiler boards!
    I'm asking this here since it's a bit of a spoiler.
    The complete edition of Kara no Kyōkai coming out at the winter comiket is going to have errors corrected,
    but does that include changes to the setting as well?
    (For example, in Tsukihime the succession of the Fujou main family is done through the passing down of techniques,
    while in Kyōkai it is determined by blood.)

    I'll answer that!
    Regarding the Fujou, the setting isn't quite the same.
    Though Rakkyo and Tsukihime have a lot of points in common, there are a few tiny differences in the details.
    One of those is the Fujou. In reality they're actually ESP users like the Asagami, Ryougi, and Nanaya. But in Rakkyo they are a magi lineage.
    Other than that... oh, right, there's Aoko's age. If Rakkyo and Tsukihime were the same world then Aoko would only be a little bit older than Tohno Shiki. The Aoko in Rakkyo has not yet gained the title of "Miss Blue", and is still training in Misaki Town.
    It's probably best to think of it as subtly shifted parallel worlds.


    その一つが巫浄。実際、浅神、両儀、七夜は超能力に類する物ですが、「らっきょ」の巫浄は魔術師の家系です から。
    他には……そうですねー、青子の年齢とか。「月姫」と「らっきょ」がまったく同じ世界だとすると、青子って 志貴よりちょい年上なだけになってしまいます。「らっきょ」での青子さんはまだミス・ブルーなんて呼ばれて おらず、三咲町で修行中だったり。

  8. 8.0 8.1 8.2 8.3 Fate/strange Fake Volume 1 - Afterword: Nasu Kinoko's Commentary
  9. The Adventures of Lord El-Melloi II Volume 1: The Man Who Devoured God - Afterword
  10. Makoto Sanda Twitter 10:16 PM JST · Aug 13, 2021Flag of Japan
  11. Eiichirou Mashin Twitter 1:53 PM JST · Apr 21, 2018
  12. Fate/strange Fake Volume 1 - Extra Chapter: Observer. Or, Character Creation translation, p.187-193
  13. Flat Escardos's Darts Trip of Himuro no Tenchi Appreciation: A Preview - Afterword
  14. TYPE-MOON BOOKS material
  15. The Bamboo Broom Diary, August 14th, 2015

    "Clock Tower 2015 is in the world of Tsukihime and Mahou Tsukai no Yoru. In that world, a certain someone XX in order to protect the present, and so the events of FGO don't happen. No one knew about his achievements but he protected both the past and the future."

  16. Keikenchi Twitter 2:16 PM JST · Dec 10, 2019Flag of Japan
  17. [v] Fate/type Redline - Glossary: First of All… [Note], p.202

    First of All… [Note]
    Do note that Fate/type Redline is not connected to any other existing work within the Fate franchise and exists within its own unique continuity.

    「帝都聖杯奇譚 Fate/type Redline」における設定は、既存のどのFate作品ともリンクしない帝都聖杯奇譚独自の設定となっておりますのでご注意くださいませ。

  18. Fate/type Redline - Chapter 11.2
  19. Fate/type Redline - Chapter 2.1
  20. Fate/type Redline - Chapter 13.1
  21. Fate/type Redline - Chapter 11.1
  22. [v] Fate/complete material III: World material - FAQ with Nasu: Miscellaneous, p.136

    Q: Are the three routes of "Fate/stay night" parallel worlds existing at the same time? I was curious since I was how it would look to Zelretch.

    Q: Are the three routes of "Fate/stay night" parallel worlds existing at the same time? I was curious since I was how it would look to Zelretch.

    A: They're parallel... sort of. But if Zelretch was observing, it'd become true, and my feelings on the matter is that I'd rather two routes disappear if one was true.
    If all of these became possible at the same time, the other routes would become meaningless.

    Q:「Fate/stay night」の3ルートで、同時に存在する並行世界なのでしょうか?ゼルレッチが見ていたら、こんな感じに見えるのかと思いましたので。


  23. Fate/kaleid liner PRISMA☆ILLYA 3rei!! - Chapter 44: "The Problematic Truth"
  24. Fate/kaleid liner PRISMA☆ILLYA 3rei!! - Chapter 17: "The Foreseen Eternity"
  25. Fate/kaleid liner PRISMA☆ILLYA 3rei!! - Chapter 18: "The Penultimate Truth"
  26. Fate/Apocrypha Volume 3: Triumphal Return of the Saint - Prologue
  27. 27.0 27.1 Fate/Apocrypha Volume 1: Apocrypha: Great Holy Grail War - Chapter 1
  28. [v] Fate/Apocrypha material - Encyclopedia: Subcategory Holy Grail Wars [Others], p.154-155 [T]

    Subspecies Holy Grail Wars [Others]
    The small Holy Grail Wars that have been recklessly happening everywhere since several decades ago in the “Apocrypha” world. Varying from those with only two Servants to wars with five Servants which, though inferior in scale to Fuyuki, are still considerably large conflicts, all kinds of Holy Grails Wars are brightly, happily and violently taken place throughout the world.
    This is because, after the Third Holy Grail War, Darnic disseminated information on the structure of the Holy Grail War, which normally should have been concealed at all costs, to other magi in order to forestall them from searching for the Holy Grail that he had stolen.
    Even for magi who lament over how the Root is just a distant fairy tale, once they learned that they could take a step… or perhaps even just half a step towards reaching it through this ritual, they ended up desperately creating Holy Grails of their own.
    Broadly speaking, out of a hundred Holy Grails made, ninety-five of them get stalled due to setbacks in the midst of constructing them, and out of the remaining finished five Grails, four end up incomplete and explode while prana is poured into them. The last remaining Grail out of them all manages to work properly, but the ritual is degraded in quality and cannot be compared to the one in Fuyuki.
    However, with the prana accumulated in the Grail, it still becomes possible to bring about miracles of varying scale. Being summoned by such a shoddy Holy Grail is a real nuisance to the Servants, though. There are many Servants who refuse the summoning or rebel and kill their Masters.
    Amongst young magi, something like a “Holy Grail War Walkthrough Wiki” has been secretly created and is used to outwit obstinate old magi by mustering their intelligence… maybe. The early period right after the subspecies Holy Grails began was called the “golden era of Assassins”, where Assassins (Hassan-i-Sabbah) were a great menace (because, on top of their prana consumption being low, killing Masters was far easier than battles between Servants, so it might have seemed like easier work in its own way), but by the middle period, countermeasures against them were naturally taken and the Hassan boom fell into decline. It’s apparently a common sight for Masters who enjoy having their Servants fight each other to easily team up just as Assassin is confirmed to be summoned.
    It is quite common in the subspecies Holy Grail Wars for the Servants to be unable to display their full power as much as in Fuyuki depending on the quality of the leylines, and, since the advantages and disadvantages of each Servant also becomes clear according to their level of fame in the land where a war takes place, it often turns into a competition to obtain the catalysts of local Servants.
    For instance, a subspecies Holy Grail War in Greece would create a struggle for a “catalyst of Heracles”, and the magi who managed to get it would win… In other words, the whole thing seems to go full circle and turn into a simple battle of magecraft between magi in the end. As a cute one-time divorcee magus said, “Rather, the whole idea of fighting that macho guy in his homeland is seriously ridiculous in the first place.”
    After the use of Heracles was forbidden as a result of that, the next war turned into a competition over the catalyst of Achilles, and so there has never been a proper Holy Grail War held in Greece. There exist terrible tales of Holy Grail Wars like this.


  29. Fate/EXTRA Visual Fanbook - Page 079
  30. 30.0 30.1
    [v] TYPE-MOON Fes. Official Pamphlet 10th Anniversary Q & A Booklet:

    Q: The concept of Tsuki no Sango is the "degenerated what if scenario" of Tsukihime 3000, but is Tsuki no Sango a potential future of Tsukihime universe?

    Q: The concept of Tsuki no Sango is the "degenerated what if scenario" of Tsukihime 3000, but is Tsuki no Sango a potential future of Tsukihime universe?

    A: Tsuki no Sango is a world where the event of Tsukihime did not occur. Different from EXTRA's "what if" scenario, the one of Tsuki no Sango is "a degenerated world where magecraft yet lingers". Tsuki no Sango has a Land of Steel type of world.

    Q:月の珊瑚の裏コンセプトが「月姫3000」で『退廃的なイフ』とされていますか、月の珊瑚は月姫世界 の未来の可能性の一つなんでしょうか?

    A:「月姫」が起きなかった世界というか。でもエクストラのイフとも違う、「魔術残ってたけど退廃的な世 界」という扱いで一つ。「月の珊瑚」はどっちかっていうと鋼の大地系です。

  31. [v] Comptiq 2004-12 issue - Fate/secret book Q & A:
    Q:Fate/stay night is a story set in the same world as Kara no Kyoukai and Tsukihime, isn't it? If that's right, then what's the temporal relationship between them?

    Q: Fate/stay night is a story set in the same world as Kara no Kyoukai and Tsukihime, isn't it? If that's right, then what's the temporal relationship between them?

    A: It's the same world. And I can't give you exact dates, but basically Fate and Tsukihime are set around the same time, while Kara no Kyoukai is a little bit further in the past.



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