Sigma (シグマ, Shiguma?, Σ) is the "True" Master of Watcher in the False Holy Grail War of Fate/strange fake. Despite having summoned Watcher, the shadows of Watcher claim that it is not meant to be a participant of the Holy Grail War, but rather a guide for Sigma himself to become the True Lancer (真ランサー?) Servant of the War "while living."
Sigma was raised by an unknown government to become part of a special forces unit that utilizes magecraft. He is the product of rape between Maiya Hisau and an unknown soldier possessing Magical Circuits to create soldiers for that unit. He wasn't given a name and was taken away from Maiya when he was a baby. He was among twenty-four children selected for the unit and given a Greek letter as code names, being forced to fire a gun when barely five years old, and enduring magical experiments. According to Francesca, as a result of the experiments he has a shorter lifespan than the normal person, but he will maintain his youthful appearance as someone in his late teens for a long time and will age rapidly when his time comes. The government, eventually collapsed with intervention from the Clock Tower to protect the secrecy of Thaumaturgy. Sigma became a mercenary, who served different people around the world, until coming under the service of Francesca and hired to become a participant of the Snowfield Holy Grail War.
Sigma treats himself as an ordinary soldier, calling himself simply Soldier A. He doesn't have any wish, desire, or anything to believe in, completely lacking faith in anything even being uncertain in his own abilities. He is rather cold, not feeling much about the death of her own mother in a similar Grail War that he is now participating. However, after summoning Watcher, Sigma starts seeing himself as more unique, making his own decisions that go against his superiors.
Sigma apparently has some knowledge of film-related details such as how he tries to hide Watcher's identity, informing others that Watcher is Charlie Chaplin, or how, when Watcher asked the young Magus if he knows about King Arthur's Holy Grail quest, Sigma responded that it's a Monty Python comedy which causes Watcher to falls silent.
Sigma is a mercenary hired by Francesca. He is told by her to become a Master, with Francesca not even giving him a catalyst, as she wants to see what the Grail itself picks. Although he is hired by Francesca, she tells Sigma to do what he wants, as it will make things more interesting. Francesca's associate, Faldeus Dioland though tells Sigma to keep in contact with him and inform him of what Servant he will summon. Sigma himself isn't interested in the Grail War, lacking a wish and only treating it as another task.
When Sigma finally summons his Servant, he is surprised to see that he has summoned numerous different beings. These beings, however, explain that they are simply shadows of the real Servant Sigma summoned, Watcher. Watcher doesn't show himself to Sigma, instead, watching over the Grail War, gathering information which the shadows then tell to Sigma. The shadows also tell Sigma that he is supposed to become the real True Lancer after he has completed several trials. Despite the unordinary circumstances, Sigma feels confident, not believing himself to be an ordinary soldier anymore.
As Sigma and the shadows continue talking the shadows eventually tell him that his first trial is about to begin, as False Assassin enters the house Sigma is in. Before Sigma even reacts, Assassin moves in front of him, questioning if he is a Master. Sigma manages to escape by distracting Assassin and jumping out of the window. As he tries escaping, he spots a girl, who he believes to be a bystander and telling her to run, endangering himself. However, the girl turns out to be a Master, named Ayaka Sajyou, who is the Master of Saber, who himself has formed an alliance with Assassin. Seeing Sigma endanger himself for a girl he doesn't even know, Saber decides to make an alliance with him, which Sigma accepts. Though allying with them, Sigma doesn't reveal the nature of his unique Servant, saying that he has summoned the Lancer Charlie Chaplin, who doesn't want to show himself.
While staying with Ayaka, Saber, and Assassin, Sigma also contacts Faldeus, also lying about his Servant, confusing Faldeus. After contacting him, Sigma talks with Assassin, who is still suspicious of him. Sigma tells Assassin that he lacks faith in anything, which is a contrast to Assassin, who is extremely religious. Assassin is though able to understand Sigma, realizing that he simply hasn't encountered anything worth believing in him. As she leaves him, she wishes that he will be able to find something to believe in. He stares at her, and the shadows tease him, asking if he has become smitten with her, which he denies.
Sigma later gets information from Faldeus of the house being surrounded which he tells to Ayaka and Saber. While they stay in the house, Sigma also informs them of the battle in the factory district between True Berserker and True Archer. Although Saber is intrigued by this battle, Sigma tells him that the battle will be stopped soon by his true employer, who is Francesca. This is true, as Francesca sent her Servant, True Caster to solve the issue.
Sigma also receives information from Watcher about Tsubaki Kuruoka, a young comatose girl who is also the Master of False Rider, who the police officers are trying to secure. Saber, Assassin, and Sigma decide to go help them, though when they arrive, True Archer and False Archer are also present, with a battle likely soon ensuing.
He was first mentioned in Fate/Zero novel. He was indirectly mentioned when Maiya confesses to Irisviel von Einzbern about being a mother. Irisviel encourages Maiya to look for her son after the Fourth Holy Grail War.
Sigma is a Spellcaster, excelling in the use of familiars. He is less of a mage, and more of a mercenary who employs magecraft to achieve his goals. He has been trained from childhood to become a soldier, making him very skilled in numerous weaponry and combat. Sigma is supposed to be the one to become True Lancer after summoning Watcher.
- ↑ 1.0 1.1 Fate/Zero - Volume 4: Act 13 -37:02:47, p.089-092
- ↑ 2.0 2.1 Fate/strange fake Volume 4, Interlude: "The Trials Begin"
- ↑ Fate/strange fake Volume 4, Interlude: "Watcher"
- ↑ Fate/strange fake Volume 3, Extra
- ↑ Fate/strange fake Volume 3, Interlude: "The Passion of the Nameless Soldier"
- ↑ Fate/strange fake Volume 4, Interlude: "The Boy Does Not Believe In God"
- ↑ Fate/strange fake Volume 4, Interlude: "Backstage at a Third-Rate Comedy"
- ↑ Fate/strange fake Volume 4, Chapter 12: "The Gods Return from Twilight"
- ↑ Fate/strange fake Volume 4, Interlude: "Parade of Treachery"
- ↑ Fate/strange fake Volume 4, Chapter 13: "At Last, a Second, and a Third"