The Magic Circuits.

Magic Circuits (魔術回路(マジック・サーキット), Majutsu Kairo(Majikku Sākitto)?)[1] are a pseudo-nervous system that spreads itself through the human body and what qualifies a person to be a Magus. They have two basic functions; one is to convert Life Force into Magical Energy and another is to allow their owner to access Greater Magic Formulae (大魔術式, Dai Majutsu Shiki?), that is, Thaumaturgical Foundations.[2] They also are paths that connect the material world to the astral plane. To perform mysteries, a Magus sends a command and Magical Energy to a Thaumaturgical Foundation through his Magic Circuits and activates one of the Magic Formulae (魔術式, Majutsu Shiki?) included in the Foundation[3] as if someone switched a computer on and sends it commands to run a computer program.[4]


Various states of Shirou's Magic Circuit.

Magic Circuits reside within the Magus’s Soul[5], and what is found on the body is just a physical expression of them that stretches itself throughout the body in a fashion similar to the nervous system.[6]

They are composed of core components, which are the actual Circuits so to say, and bypasses that connect those components to the brain. Magic Circuits do not change and once damaged they cannot be repaired. Because organic activity is necessary for the operation of Circuits, it is a common mistake to think that they are literally a part of the magus body. There are rare occasions in which the Circuits continue working even after the practitioner’s body has ceased all vital functions.[7] In these cases, destruction of the brain is necessary to stop the Circuits. Their Quality and Quantity are ranked through letters like Magecraft, and their Composition often varies between magi.

Like any other organ, the number of Magic Circuits that one possesses is determined at birth and cannot decrease or increase naturally, meaning that those from older lineages will be more powerful, but it is possible to change that number artificially through a number of methods. One of those methods is through the establishment of a mystic pass between two magi from which the Circuits can transferred. As the Circuits are located in the soul, a fusion of body and mind is required during the transplant. However, the process carries the same risks and complications as a transplant of organs. Furthermore, as the Magic Circuits become unstable if tampered while in use, there is a possibility of mutual destruction if a contract similar to that between a magus and his familiar has not been established beforehand.

For that and other reasons, lineages of magi seek not to tamper with the Circuits of their members while they are alive, but rather try to produce descendants with the greatest "extra" number of Magic Circuits possible. Note that number is not everything, and quality and precision of the Circuits are also an important factor that differs from lineage to lineage. The Aozaki bloodline is known for producing magi with a low quantity of Magic Circuits, but the great quality of their Circuits is more than enough to compensate for that. Meanwhile, the Barthomeloi possess a powerful brand of Magic Circuits known as Blue Blood: Noble Magic Circuits (貴い魔術回路(ブルーブラッド), Tōtoi Majutsu Kairo(Burū Buraddo)?).

A normal person rarely acquires Magic Circuits but in these cases they are considered as sudden mutations. While Kirei Kotomine was born with sudden Magic Circuits not of his lineage, he is not of this type. Kirei's Circuits were a gift from the divine sacrament, rewarding his father, Risei Kotomine, for years of pious worship. Kirei was born with "the right to recreate the miracles in the divine sacrament". This "right", in other words, was the Magic Circuits.[8]

Known numbers of Magic Circuits by characters:

Still, the Circuits are ultimately something unnatural for the human body and their activity will cause pain and numbness to the magus. Their very presence in the human body is something uncommon and an ordinary person will have little to none. Also, the use of Magic Circuits increases the magus bodily temperature, which is what allowed Kiritsugu Emiya to discover enemy Masters on the battlefield through the employment of a thermal sensor during the 4th Grail War.[15]

Magic Circuits are “opened” when magical energy is run through them for the first time. Based on their experience at that time, a Magus makes their own mental trigger to activate their Circuits at will from then on. For this reason, the triggers are different from each other and in an extreme case, self-injury can be regarded as a switch.[12] An unexpectedly large number of magi have sexual excitement as their triggers and moreover many of them rely on drugs.[16]

Known mental triggers by characters:

Prior to the Fifth Grail War, Shirou believed that he had to “make” a new Circuit every time he wanted to perform Magecraft. In each attempt to do so, he temporarily (and inadvertently) converted parts of his nerves into makeshift Magic Circuits. A very dangerous procedure, as failure would result in his body breaking down from the inside out and even with success the resulting pain would be comparable to inserting a hot iron rod into the spine. Furthermore, when his natural born Circuits were finally opened, his nervous system went haywire due the sudden intake of energy. At first, neither of his teachers of Magecraft (Kiritsugu and Rin) noticed that habit of his.

A lesser known function of Magic Circuits is that they can be used to record and store information, in a manner not too dissimilar from computers or smartphones,[19][20] like replaying scenes seen in one's head.[21] Any mage that is at least somewhat capable use them as a calculator in addition to their brains when solving problems.[22]


Differing from the Magic Circuits of regular humans, Artoria and Siegfried when he was alive have a Magic Core (魔術炉心, Majutsu Roshin?) granted by their Dragon blood. Its capacity is far greater than any human can achieve. While a magus' body can be considered a machine which creates magical energy, Saber's Core acts as a factory which creates magical energy. Gray also gets a dragon Magic Core after Artoria is summoned as Saber in the Fifth Holy Grail War, with the summoning affecting Gray's body due to her nature, and turning her more into a perfect clone of Artoria. Greater Grail is also considered as special one.

A Magical Energy Reactor (魔力炉, Maryoku Ro?) generates enormous magical energy completely without its user's Circuits. Prelati's Spellbook has one within it[23] and Kayneth El-Melloi Archibald places three ones in his Magical Workshop on the Fuyuki City Hyatt Hotel. Ciel can temporarily transform her Idea Bloods into Magical Energy Reactors in order to replenish her own mana, though the cost comes at her own humanity.

For Divine Patterns, see Fairy.

Regression to the Age of Gods[]

Beings like Lugh Beowulf and Arcueid Brunestud have Regression to the Age of Gods (神代回帰, Jindai Kaiki?, also called Reversion to the Age of Gods) as their own style of Magic Circuits. It represents the extent at which they are capable of producing Mysteries that existed on Earth before Magic. They are ranked with quantifiable letters like Magic Circuits. Their Quality ranking represents "how distant from what humans are capable of" when reproducing their pure Mysteries. Their Quantity ranking represents power, the higher the quantity, the greater the degree of influence over the surrounding environment. C rank Quantity allows for the display of power over a village at most. Their Composition represents the era of the "Mystery", such as Runes, Kabbalah, and Black Magic do so in magecraft. While similar in concept, things like Alice Kuonji's Ploys are not from the Age of Gods and cannot be assigned a number in Regression to the Age of Gods.[24]


  1. Fate/stay night - Day 1: One day - Training (Magic Circuit)
  2. 2.0 2.1 2.2 2.3
    [v] Kara no Kyoukai Special Pamphlet - Encyclopedia: Magic Circuits [Others], p.039 [T]

    Magic Circuits [Others]
    The pseudo-nerves existing in the body of a magus.
    They are the paths that convert life force into magical energy, as well as the paths which connect to the foundations underlying Grand Rituals.
    The number of Magic Circuits is determined at birth. Mage lineages will resort to any means to alter themselves in hope of giving their descendants just one more Circuit.
    This is why magi from older lineages are more powerful.
    In terms of the number of Magic Circuits, and the quality of the lineage, Cornelius Alba is undoubtedly a first rate magus.
    In fact, neither Aozaki Touko nor Araya Souren have many Magic Circuits. Touko has about 20, Araya about 30.
    Still, the two are considered geniuses: Touko has talents that are independent of her lineage. Araya's overwhelming power is probably a result of the anguish that he ceaselessly accumulated through the ages.


  3. [v] Fate/complete material III: World Material - Theory of Magic - Magecraft, p.040

    Keywords to learn about Thaumaturgy
    Determines the orientation of the magic that the magus is skilled in

    One of the factors determining the effect of one's magic. There are multiple genres like reinforcement and projection.

    •Magic foundation
    System engraved in the world in advance, which renders magic usable. Takes the form of academia and religion.

    The orientation at the time that an event occurred.
    The origin is what defines the existence as an existence. In magery, it also is used under the meaning of alignment.

    •Magic formula
    Something included in a magic foundation and in which the function of magic is recorded.
    The magus sends a command to the magic formula, puts magic power into it, and thereby activates the function of magic incorporated into the formula in advance.


  4. [v] Kara no Kyoukai Special Pamphlet - Encyclopedia: Magecraft [Others], p.038-039 [T]

    Magecraft [Others]
    A general term representing activities that artificially re-enact Mysteries/Miracles.
    Although there were some differences depending on traditions and schools, the basic principle was still "the transformation of the magical energy that exists within the practitioner or the environment".
    The practitioner would issue Commands according to the Foundation (System) of his school, and this would cause the execution of a predetermined Program.
    Magical energy was the electrical current required to deliver the command.
    Although magecraft gave the impression of omnipotence, it fundamentally produced Mystery through the principle of equivalent exchange.
    It was possible to transform one thing into another, but it was impossible to produce something from nothing.
    However, the essence of magecraft as a discipline was to challenge that "Nothingness", and endeavor towards the impossible. Large-scale spells such as the so-called Grand Sorceries, Grand Rituals were really purposeless if not for attempting to reach " " (Kara) or True Magic.
    Kara no Kyoukai was a story of one magus' attempt at challenging "Nothingness".

    が、その『無』、あり得ない事に挑むことが魔術という学問の本質である。大魔術、大儀式と呼ばれる大掛かりな魔術は「 」、魔法に至る為の挑戦に他ならない。

  5. Fate/stay night - Heaven's Feel (route) - True End: Return to the Spring
  6. [v] Fate/complete material III: World Material - Theory of Magic - Magecraft: Magus, p.041

    •Magic circuit
    Magic circuits are the pseudo nerves that a magus has inside himself. These are paths that generate magic energy and access the magic foundation engraved in the world. Magi make magic energy with the magic circuits and use the magic energy to run the magic foundation and thus put magery into effect. To do either of these, the magic circuits are necessary.

    As suggested by the description pseudo nerves, these are split into cores and lines joining these together and are spread throughout the body.

    The number of magic circuits are fixed at birth and the number won't increase by other than external factors.

    •Magic crest
    The product of stamping the anchored mystery that a magus had spent his entire life building up. Can be said to be mystical inheritance that defines the magus line as a magus line. While the inheritor is young, it is necessary to implant this little at a time while at the same time having the body adjust to the magic crest by medicine and rituals. The magic association also has technology for extracting just the magic crest from the body and storing it.

    •Magus alignment
    What determines what kind of attributes a magus' magic is going to be likely to have, or what kind of magic the magus is going to have good chemistry with, is going to be the element aligned with the magus.
    In addition to the five great elements of earth, water, fire, wind, and sky, there's the imaginary elements of Hollow and Nothing, for a number of seven.
    Some of the five elements will differ according to the school of magic. A famous one is a style in which the five great elements are formed from wood, fire, soil, metal,and water.
    Basically, one magus has one alignment, but sometimes there are magi with two alignments (like fire and earth, wind and water) and there are also those called "Average Ones" who have all the five great elements.

    Matou Sakura normally would have been a holder of the imaginary element of Emptiness. However, through her magic training, hers had been changed to the water alignment of the Matou line, so she couldn't exhibit her true talent.

    Normal alignments
    Five great elements Earth One of the two alignments of Kiritsugu. Kiritsugu exhibited his attribute of combining and used magic which combined the wounds of an enemy in a different form than normal, and made them unhealable.
    Five great elements Water The alignment that the Matou magi have had for generations. Matou exhibit the attribute of absorption and have passed it on. Sakura's alignment changed from Emptiness to water.
    Five great elements Fire The alignment of Tokiomi and also one of the two alignments of Kiritsugu. It is the symbol of life and death and has good chemistry with destructive magic.
    Five great elements Wind One of the two alignments of Kayneth Elmelloi Archibold. There are few magi with wind as an alignment
    Five great elements Sky An element which makes up celestial bodies that is newly added as a fifth element to the four great elements of earth, water, fire, and wind. This is, in other words, Ether.
    Imaginary Elements Hollow The alignment that Sakura was born with. Defined, in magery, as that "which is possible but is not in the physical plane". Also called imaginary numbers.
    Imaginary Elements Nothingness Like Hollow, the alignment of an imaginary element. In magery, defined as that "which is not possible, but materializes". Has a different meaning that the "nothing" of physics and math.

    •The absoluteness called Origin
    If alignment determines the root of one's magic, then even deeper than that, is the origin which determined the root of one's existence. The origin is not only for magi, but is the orientation that all things are born with and it's existence itself is thought absolutely necessary.
    Those magi with an origin that is strongly expressed outwardly are sometimes removed from the normal alignments and there are times that the origin itself becomes the alignment. Most of those magi exhibit their talents as extreme specialists.
    Because of that, it's said that they can reach higher grounds than normal magi.

    Shirou Emiya's origin is "Sword" and his alignment as a Magus is also "Sword". He is unable to use magic of the five great elements with precision because he doesn't have any of them as an alignment, but it does allow for the manifestation of "Unlimited Blade Works."

    •Noble Colors
    Of the alignments, wind is called "noble" and fire is "normal". By the way, the term "Noble Colors" is used to refer to special and innate things where he workings of the magic circuit are close to the movements of a celestial body (normally they're closer to the movements of the crust), and is innate and special.
    Noble Colors are often used to refer to mystic eyes, and Rider's petrifying mystic eyes are also a noble color.

  7. [v] Tsukihime Dokuhon PlusPeriod - TSUKIHIME Dictionary: Magic Circuit [Term], p.188-189

    Magic Circuit [Term]
    The foundation for setting up Thaumaturgy. There are two types, but here it refers to the quality within a human body that makes a magus a magus.
    Magic circuits are responsible for converting life force into magical energy, and for connecting to the underlying grand sorcery formula.
    Basically, sorcery is a formula that causes nature interference by starting up and stabilizing a "rule already established in the world" with magical energy. Or to put it another way, the "rule" is a car, and the "magical energy" is the gasoline that makes it run.
    In order to start up sorcery, three things are required:
    the necessary amount of magical energy, a key (password/spell/code), and magic circuits to inject the magical energy into the "engine".
    If we assume for a moment that magical energy is electricity, then magic circuits would be both the reactor that produces that electricity, as well as the pipelines for running the system.
    Because vital activity is indispensable to the operation of this reactor, there is a common misconception that a magus' body = magic circuits. However, though quite rare, magic circuits that continue rotating on their own even after the practitioner's vital activity has stopped do exist.
    The reason that an individual's magical energy (od) will be regenerated even if is totally used up is because the magic circuits are still operating. But on the other hand, without magic circuits, magical energy (od) will no longer be generated at all.
    They are spread throughout the entire body as pseudo-nerves, and can basically be divided into cores, and pipes that connect these cores together. The pipes are similar to the synapses within the brain, constantly breaking off and reconnecting, but the cores never change.
    Strictly speaking, these cores are the actual magic circuits.
    They are considered to be a sort of internal organ, that will never increase or decrease in number. Of course, extracting and transplanting them is technically possible, but just like implanting an extra organ into a human body it should go without saying what will happen if you try it.
    Magic circuits, once lost, will never return.
    As for what magi actually use these magic circuits for, well, that's covered in a different story.


  8. [v] TYPE-MOON Fes. Official Pamphlet 10th Anniversary Q & A Booklet:
    Q: Kirei's wife Ortensia is covered with wounds in the design draft, is it because she has a body similar to Caren's? Also, Command Spells appeared on Kirei due to the fact that he somehow possesses Magic Circuits despite being born in a non-magus lineage. Does this mean Caren also has Magic Circuits?

    Q: Kirei's wife Ortensia is covered with wounds in the design draft, is it because she has a body similar to Caren's? Also, Command Spells appeared on Kirei due to the fact that he somehow possesses Magic Circuits despite being born in a non-magus lineage. Does this mean Caren also has Magic Circuits?

    A: Kirei's wife is an albino, and is immunodeficient. As a result, she can die from even a tiny wound, thus her body appears tattered. What Caren inherited is the aspect of "prone to be plagued by illnesses". This is truly an ordeal given by God.
    About the Magic Circuits, a normal person rarely acquires Magic Circuits. You can consider such cases sudden mutations. However, Kirei is not of this type. Kirei's Circuits were a gift from the divine sacrament, rewarding his father Risei's years of pious worship. Kirei was born with "the right to recreate the miracles in the divine sacrament". This "right", in other words, was the Magic Circuits. Caren did not inherit the Circuits.

    Q:綺礼の奥さんであるオルタンシアさんが設定画で手当ての跡だらけなカレンと同じ体質だからなのでしょ うか。あと、綺礼に令呪が現れたのは元々魔術師の家じゃないけどたまたま魔術回路を待っていたということで 、カレンにもあるんでしょうか?

    A:奥さんはアルビノで、免疫機能が欠如した人でした。なので些細な傷でも死に繋がるし、体もボロボロで した。カレンに受け継がれたのは”病魔に憑かれやすい”という在り方。神の試練ですな一。
    魔術回路ですが、これは一般人にも稀に待って生まれる人がいます。突然变異と思ってください。綺礼はその類 ではありませんが、父・離正が長年の信仰によって得た秘蹟の恩恵で、” 秘蹟を再現する資格”をまって生まれました。秘蹟を再現する資格、なんで言ってますが、ようは魔術回路です 。カレンには受け継がれていません。

  9. Character material - Tohko Aozaki: Introduction, p.24
  10. 10.0 10.1 Character material - Aoko Aozaki: Explanation, p.9
  11. 11.0 11.1  Lord El-Melloi II Case Files Volume 1: case. Adra Castle Separation - Chapter 3 Part 2 (translated by TwilightsCall) 
  12. 12.0 12.1 12.2 12.3 12.4
    [v] Fate/side material - Encyclopedia: Magic Circuits [Magecraft], p.073 [T]

    Magic Circuits [Magecraft]
    Pseudo-nerves within the body of a magus.
    Magic circuits are responsible for converting life force into magical energy, and for connecting to the underlying grand sorcery formula.
    Because the number of magic circuits a person has is fixed at birth, magi lineages do what they can to improve themselves and create an heir with even one more magic circuit.
    Once the magic circuits have been opened for the first time, the practitioner can switch them on and off at will.
    Each practitioner visualizes the flipping of this switch in their own particular way. For Shirou, the image is that of a gun's firing hammer, while for Rin it is stabbing a heart with a knife.
    This image tends to be related to how the circuits were opened for the very first time, so there even those who can only open their circuits through sexual arousal or self-harm.
    By the way, Shirou's number of magic circuits is an unexpectedly high 27.
    Rin, on the other hand, has 40 main circuits, while her sub-circuits are 30 each.


  13. 13.0 13.1 Fate/stay night - Heaven's Feel route - Day 16: FINAL - Gem Sword Zelretch
  14. Fate/stay night - Heaven's Feel route - Day 11: beautiful (II) - Tohsaka Rin (III)
  15. Fate/Zero Volume 1: The Untold Story of the Fourth Holy Grail War - Act 3 Part 1 -162:26:39
  16. 16.0 16.1  Lord El-Melloi II Case Files Volume 1: case. Adra Castle Separation - Chapter 4 Part 1 (translated by TwilightsCall)
  17. Lord El-Melloi II Case Files Volume 3: case. Twin Towers of Iselma (Lower) - Chapter 2 Part 3
  18. Fate/strange Fake Volume 7
  19. Clock Tower 2015
  20.  Lord El-Melloi II Case Files Volume 4: case. Mystic Eyes collection train (Upper) - Chapter 4 Part 2
  21. Lord El-Melloi II Case Files Volume 2: case. Twin Towers of Iselma (Upper) - Prologue
  22. Lord El-Melloi II Case Files Volume 9: case. Grand Roll (Middle) - Prologue
  23. [v] Fate/Grand Order - Gilles de Rais (Caster) Profile [T]

    Gilles de Rais - Caster

    Illustrator and Voice actor
    Illustrator: Azusa
    Voice Actor: Tsuruoka Satoshi

    Strength: D
    Endurance: E
    Agility: D
    Mana: C
    Luck: E
    Noble Phantasm: A+

    Personal Skills
    Mental Pollution: A
    Eye for Art: E-

    Class Skills
    Territory Creation: B

    Noble Phantasm
    Prelati's Spellbook: Textbook of the Spiral Sunken Castle
    Rank: A+
    Type: Anti-Army Noble Phantasm

    A French noble from the 15th Century. Having repeatedly committed the deed of abducting young boys from the vicinity of his domains and then disgracing・slaughtering them one after the other, things reached the point in which he became known as the model for the later fairytale "Bluebeard".

    Level 1 Bond
    Height/Weight: 196cm・70kg
    Source: Historical fact
    Region: France
    Alignment: Chaotic Evil  Gender: Male
    A holy monster that sought for God more than anyone else.

    Level 2 Bond
    He was once the owner of a highly pious heart, he fell of deep despair and lost sight of God after Jeanne D'arc was executed as a heretic. His cruel deeds were also a means to prove the absence of God (who supposedly punished such vices).

    Level 3 Bond
    "Textbook of the Spiral Sunken Castle"
    Rank: A+  Type: Anti-Army
    Prelati's Spellbook.
    A grimoire which in itself is equipped with a magic reactor.
    It summons monsters from another world in an inexhaustible supply.
    Gilles de Rais is not a legitimate magus himself and has no groundings in magecraft, but in exchange this grimoire can exercise magecraft.

    Level 4 Bond
    At first, Gilles got involved in alchemy along with his friend, the cleric François Prelati, in order to cover up for financial difficulties, but at some point he lost sight of the original purpose and began to concentrate on summoning of demons.

    Level 5 Bond
    As others began fearing that he would sell over his domains to an enemy nation in order to raise money, as an excuse for the seizure of his territory, Gilles was convicted for his past misdeeds and executed. The censures towards his blasphemy and cruel deeds were all nothing but political pretenses.

    This man, who couldn't help but hold suspicions against God exactly because he extolled God too much and infatuated himself with scornfully curse God, was finally destroyed without being judged by God. Probably, only a Master who shows understanding towards such zeal and despair can perfectly employ him as a Servant.

    ジル・ド・レェ - キャスター



    精神汚染 A
    芸術審美 E-

    陣地作成 B



    属性:混沌・悪  性別:男性


    ランク:A+  種別:対軍宝具




  24. [v] TYPE-MOON Fes. Official Pamphlet 10th Anniversary Q & A Booklet:

    Q: What do the Quality/Quantity/Composition of Regression to the Age of Gods mean in Beowulf's profile? Do Ploys, Arcueid, and Heroic Spirits have such designations? And what would their number be?

    Q: What do the Quality/Quantity/Composition of Regression to the Age of Gods mean in Beowulf's profile? Do Ploys, Arcueid, and Heroic Spirits have such designations? And what would their number be?

    A: Regression to the Age of Gods represents the extend at which they are capable of reproducing the Mysteries that existed on Earth before True Magic. Consider it to be like that, their own style of Magical Circuits. Quality represents "how distant from what humans are capable of" their pure Mysteries are. Quantity represents power. The higher the quantity, the greater the degree of influence over the surrounding environment. Since Beowulf only has a quantity of C, he can only display his power to an individual, or over a village.
    Composition represents the era of the "Mystery". In terms of magecraft, it would be like Rune, Kabbalah, Black Magic and such.
    Ploys are not of Age of Gods, so they cannot be assigned a number in Regression to the Age of Gods.
    For Arcueid... Princess Arcueid should qualify. "Quality: B Quantity: A++ Composition: Before Common Era, pseudo-deified natural phenomenon"


    アルクは......姫アルク状態ならアリ。「質:B 量:A++ 編成:西暦以前までの、擬神化される自然現象」といったところ。