Black Key

• Black Keys.
• The Azure Black Keys (青の黒鍵, Ao no Kokken^?) Craft Essence from Fate/Grand Order.
• The Verdant Black Keys (緑の黒鍵, Midori no Kokken^?) Craft Essence from Fate/Grand Order.
• The Crimson Black Keys (赤の黒鍵, Aka no Kokken^?) Craft Essence from Fate/Grand Order.
• Noel's unique Black Keys.

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Black Keys (黒鍵, Kokken^?) are a Sacrament of the Church, one of their many charms used against demons and Vampires.

History

In 300 A.D., an era said to be when Dead Apostles were the most rampant, turning them back into corpses and reverting them to dust was the Holy Church's mission. But in that era, there was no high-firepower weapon capable of eradicating a Dead Apostle's body in a single strike. The most effective measure was shutting them into a building or forest, setting it aflame, and burning it until their blood was used up. However, the Church would bankrupt itself by doing this each and every time.

At the time, someone hailed as the pinnacle of swordsmen whilst also a priest proposed a weapon that was "mass-producible, easy to transport, with immediate effectivity that kept casualties to a minimum". This was the Scriptural Weapons, of which the Black Key was the first to be created. Instead of adding on anti-heresy effects by inscribing a weapon with prayers, the groundbreaking idea was to instead turn the scripture itself into a weapon, making it a deadly anti-heresy poison.

By the 9th century, Black Keys settled into their current form, as the most outstanding Scriptural Weapon, beloved and used widely. However, since they are hard to use, as the years went by they became inadequate in facing the ever strengthening Dead Apostles. As civilization developed, and firearms could be produced, the number of Black Key users started decreasing. In 1450, with the advent of the printing machine invented by Gutenberg^WP, the Black Keys had a slight recovery in their popularity, but unable to compete with the simplicity of guns, they demoted from a main-weapon to a sub-weapon that "you could pass off as having in place of a talisman". Since then, in the Church, Black Keys became an enthusiasts' weapon "used by choice for devoted adherents only".

Principles

They take the form of long and slender rapier-like swords with blades measuring over one meter and extremely short hilts, looking more likely to be used to thrust than slash at the opponent although Hansa Cervantes shows them to be capable of slashing through concrete. Weighing one kilo, Black Keys are too thick and oddly-balanced, feeling heavier towards the tip, to use as melee weapons in general, and they seem more like Dirks made into swords or arrows even to someone who does not know of their true nature. But while they may look like blades, they're actually prayers: Sacraments of the Holy Church, created with the lament for the dead; litanies, as their base. The part that looks like a handle is actually the cut-out page of a manuscript: Executors use their own Magical Energy to harden it into the shape of a handle so they can carry it around with them. During combat, they pour their Magical Energy into it, switching it over into Automatic Baptismal Mode, which just coincidentally happens to look like a blade. With low effectiveness as swords despite their appearance, and their great length, their true usage is exclusively as throwing weapons likened to bullets rather than for swordplay.

Despite being a basic weapon of the Holy Church, they are mostly considered to be a symbolic weapon for Executors that not many favor due to the difficulty in learning how to handle them and their weak attack power. As such, it is said to be a niche weapon favoured only by pious believers, with most Executors preferring to use the Ash Lock instead.

Those who wield them often hold multiple Black Keys at once in a "fan formation" between the fingers of each hand, and an expert like Kirei Kotomine can wield up to four in one hand. They can be thrown singularly or all at once with great accuracy and speed, Kirei notably able to prepare and throw a single Black Key in 0.3 seconds and perform four separate throws in 0.7 seconds. Primarily being throwing weapons, either directly like arrows or throwing them in a spinning arc to curve towards their target like a boomerang, their length makes defending against short knives and daggers hard due to the lack of balance, so Kirei prefers to abandon them to use his Bajiquan instead in such situations. Experts and chosen Executors generally manifest the blades from Magical Energy, carrying around only hilts in numbers up to the hundreds hidden under their robes in some cases. Ciel passes Magical Energy through pages of the Bible to manifest them, while Kirei does not seem to apply any special method. The blade is a semi-solid formed by Magical Energy, so they are half spiritual objects able to be over-filled with Magical Energy to increase their size more than twice over. When Kirei uses a Command Spell to forcibly fill them, it surpasses their limit to allow them to block a bullet from a Contender at the cost of their subsequent destruction. It is possible for non-Church members to use them as well, such as Shirou Emiya using Reinforcement to make one as "hard as diamond."

For those that have completely abandoned their humanity, of which Dead Apostles are most representative, being exterminated through words isn't possible, because their souls are no longer capable of understanding the meaning of those words. As the ways of man are only applicable to man, the words of the Lord won’t reach those that have become Dead Apostles. The mechanism behind Black Keys is that the prayers are inscribed onto the body, thus rewriting its rules into proper ones. Though the polluted soul cannot be saved, at least the physical body can be turned back to human by these prayers; thus, Dead Apostles that are struck by a Scriptural Weapon are compelled to 'remember' their body, even if only that part of them, and then terminate. As Keys of Providence, Black Keys call forth the original laws of nature Vampires were subject to as humans, thus preventing them through purification from healing the wounds made with this weapon.

Emphasizing on the ability to intervene spiritually against "evil", Black Keys focus less on physical attack power, even affecting powerful Spirits like Servants to some degree should they be struck. It is not enough to inflict any sort of fatal injury to them no matter how much Magical Energy is put into them, but they can be used to distract or pin them for a brief moment under the right circumstances. Being half-spiritual, they can naturally pierce even iron. Those used by Shirou Kotomine, a "sham of a Saint" and Servant, are noted to be much more powerful and "abnormal" against Vlad III's Legend of Dracula compared to regular Executors.

In the original Tsukihime continuity, the Iron Plate Effect (鉄甲作用, Tekkō Sayō^?) was considered a secret throwing technique of the Burial Agency, that utilizes martial arts to increase the force of impact dozens of times to allow them to bore through even reinforced concrete walls and hit an enemy with enough force to be likened to being struck by a car. There are several other special throwing techniques that can be applied by engraving them with spells to enchant them. Someone like Ciel is able to use them without impunity due to not being a believer, having inherited the knowledge from Michael Roa Valdamjong. The Cremation Rite (火葬式典, Kasō Shikiten^?) causes the target to burst into flames upon being pierced, the Internment Rite (土葬式典, Dosō Shikiten^?) causes petrification upon the target being pierced, the Mummification Rite (風葬式典, Fūsō Shikiten^?) desiccates the target upon being pierced, and the Excarnation Rite (鳥葬式典, Chōsō Shikiten^?) causes countless crows to descend upon the target. Ciel also demonstrates an unnamed ability that immobilizes the target upon the blade piercing their shadow. She mentions that the "shadow will struggle just as hard" not to separate from the target as they attempt to escape from the binding, and only she can remove the Black Key to free them.

In the Tsukihime Remake continuity, Ciel is once again shown using the Iron Plate Effect, Cremation Rite, Internment Rite, and Shadow Pinning abilities, but refers to all of these as standard throwing techniques developed by the Church for use with the Black Keys. She also list other examples of throwing techniques, such as Time Skipping and Conclave, and that many other variations exist as well. While the Iron Plate Effect remains a secret martial arts technique of the Burial Agency rathern than a form of Magecraft, the spells that can be engraved on the Black Keys now appear to be rites of the church rather than heretical knowledge Ciel obtained from Roa. The Black Keys used by Noel, while having the same properties as normal Black Keys, have an unusual variant appearance, looking more like iron stakes than slender swords, and are highly specialized towards thrusting.

In Tsukihime's manga adaptation, Ciel is capable of controlling the Black Keys' movements telekinetically, and manipulating large amounts of them at once to attack a single target. Her Tsukihime Remake counterpart displays similar abilities, being able to destroy a large force of The Dead using hundreds of Black Keys that she commands to fall from the sky like rain, with not one weapon missing its target. Shirou Kotomine was able to instantly change the direction and momentum of Black Keys that he threw or deflected by incanting the word "Set", whereupon glyphs would appear from the bottom of the hilts, freezing them in mid-air, then propelling them towards a target. He also demonstrated the ability to greatly enhance their size, throwing them into the ground wherein a burst of magic they would grow to several times the size of a person. He used this to briefly block Frankenstein during his retreat. His adoptive brother Kirei has also been seen using the same "Set" incantation during his fight with True Assassin. Karabo Frampton is able to use his Black Keys to channel Magical Energy into Ley Lines.

Users

• Ciel (Remake)
• Kirei Kotomine
• Shirou Kotomine
• Hansa Cervantes
• Sunao Sugata
• Karabo Frampton
• Angelo Braga
• Noel (uses an unusual variant form)
• Shirou Emiya (Miyu's World) (Only used once)