Xi Jianxi

Biodata

Feature	Value
Name	Xi Jianxi (汐见天溪)
Alias(es)	“Tyrant”; falsely claimed disciple of Touko Aozaki 3 1
Species/Race	Human magus
Gender	Male
Affiliation	Mage’s Association; Master in the Fuyuki Holy Grail War
Occupation/Role	Magus, combat specialist, adoptive father, magic tutor
Status	Alive 50
First Appearance	Chapter 1

Background

Xi Jianxi survived repeated ambushes in the Shadow Realm through sheer endurance, gradually developing the ability to predict attacks, evade vital strikes, and counterattack with machine-like precision. After meeting the realm’s Queen, he was placed onto an unknown destiny and later received a legitimate Mage’s Association registration as a reward for leaving the realm. 1

He was accepted as Scathach’s disciple and subjected to her harsh instruction in rune magecraft and martial arts. The extent of his time in the Shadow Realm is unclear to him; he later chose to count the year he joined the Mage’s Association as his eighteenth birthday. 2

Before settling in Fuyuki, Xi Jianxi adopted Kallen Ostia after Kirei Kotomine entrusted his daughter to him following his wife’s death. A System-issued mission later compelled Xi Jianxi to adopt Sakura Tohsaka as well. He presented himself to Tokiomi Tohsaka as Touko Aozaki’s disciple to explain his knowledge of Original Runes and puppetry, though this claim was false. 18 1

Over two years, Sakura came to accept him as her father and took his surname. Xi Jianxi taught her magecraft from his workshop, including the Primal Runes he learned from Scathach. 2

Appearance

Xi Jianxi appears to be a young man in his twenties, with a gentle but tired smile. Despite years passing after the Holy Grail War, his appearance remains notably unchanged. 5 48

• Slender build, though his physical durability and strength exceed those of ordinary magi. 10 18
• Often appears sleepy or disheveled at home, particularly after staying up to manage Holy Grail War matters. 2 23
• Maintains himself through magecraft and jokes that magi should know how to preserve their appearance. 48

Personality

Xi Jianxi is outwardly relaxed, sarcastic, and frequently reluctant to involve himself in trouble. He initially treats the Holy Grail War as an unwanted obligation, postponing strategy discussions in favor of sleep and openly resenting the System that forced him into participation. 2 3

Despite this demeanor, he is highly pragmatic in battle and unusually respectful toward Heroic Spirits. Rather than treating Morgan as a disposable familiar, he addresses her by name and recognizes Servants as historical and legendary figures deserving of respect. 5

Fatherhood is central to his decisions. He worries about Sakura and Kallen’s safety, education, and future, though he considers himself unqualified for the role. He does not demand that his daughters conform to simple moral expectations; instead, he wants them to have “good tomorrows” and accepts responsibility for guiding them. 14 23

Abilities & Skills

Original Rune Magecraft

Xi Jianxi uses Original Runes learned through Scathach’s training. His body bears rune inscriptions that draw mana from the atmosphere and allow him to sustain high-output magecraft. 3

• Uses Hagalaz to turn a thrown pebble into an explosive freezing attack. 7
• Inscribed the “Shallow Waters of the Four Branches,” a Celtic warrior vow that permits neither retreat nor defeat. 7
• Uses the first Original Rune to dull and weigh down weapons, preventing Kayneth’s Mercury Dress from harming him. 21
• Uses Ansuz, the seventh Original Rune, to suppress flames and other phenomena. 21
• Activated all eighteen Runes around the thirteenth protective Rune to endure the aftermath of Gilgamesh’s Enuma Elish. 40

Great Magecraft

His large-scale spells can threaten Servants and overwhelm conventional magus defenses.

• Thunder Reign — powerful lightning magecraft used against Lancer. 9
• Titanomachia — fire-based Grand Magic that burned through Kayneth’s blizzard and turned ice into steam. 21
• Ice magecraft capable of freezing broad areas, including the ground and lake surrounding the Greater Holy Grail. 20 45
• Eldritch Blast — an explosive beam of magical energy. 10
• Healing magecraft sufficient to treat injuries sustained by himself and Artoria after their clash with Gilgamesh. 40

Great Source Mana Draw

Xi Jianxi can draw mana directly from the World’s Great Source, treating ambient mana as readily as breathing. This lets him sustain both his own high-output magecraft and Morgan’s actions without relying on an artificial Mana Reactor. 20

Spearsmanship and Martial Arts

Scathach trained Xi Jianxi in broad martial disciplines, with spear combat being his most refined specialty. His speed, reactions, and technique allow him to confront Servants directly. 10 35

• King’s Pawn — spear technique used to redirect Gilgamesh’s launched Noble Phantasms and escape encirclement. 10
• Capable of reading a Servant’s attack trajectory and countering at close range. 1 7
• Defeated Diarmuid in a direct spear duel with the Demon Spear. 22
• Can fight effectively barehanded, overpowering and throwing Kirei Kotomine in close combat. 18
• Possesses functional swordsmanship, used with Morgan’s transforming weapon against Hassan’s divided bodies. 35

Spatial Movement and Flight

Xi Jianxi employs rapid short-range spatial transfer in combat, appearing behind opponents in flashes of light. 11

• Uses long-range transfer methods to reach allies and battlefields quickly. 14
• Demonstrated genuine aerial flight during the final battle against Gilgamesh. 43
• Used the Wind King Barrier and Avalon in aerial combat against Enuma Elish. 44

Noble Phantasms and Morgan’s Magecraft

Xi Jianxi possesses a true Noble Phantasm left to him by Scathach, though he normally keeps it as a trump card rather than using it as a summoning catalyst. 22

• Red Spear — Xi Jianxi’s personal spear-shaped Noble Phantasm. 21 40
• Gae Bolg Alternative — a new form used to pierce Gilgamesh’s spiritual core. 44
• Learned Morgan’s cloning magecraft and split himself into five bodies to escape Enkidu’s binding chains. 44

Equipment / Weapons / Items

• Red Spear — his personal Noble Phantasm and parting gift from Scathach. 22
• Demon Spear — a black spear provided by Morgan; used to defeat Diarmuid. 22
• Command Spells — originally forced upon him for the Holy Grail War; he later transferred four Command Spells to Morgan. 24 42
• Workshop — a Fuyuki residence and magical base equipped with barriers, magic crystals, a summoning circle, and space for Sakura’s instruction. 2 24
• Familiars — including a crow used to track Rin Tohsaka. 24

Relationships

• Morgan le Fay — His summoned Servant and eventual contract partner. Their relationship begins with a public pretense of marriage, develops through mutual trust in the Holy Grail War, and culminates in Xi Jianxi asking her to remain with him under a new contract. 5 41 46
• Sakura Tohsaka — Adoptive daughter and magic student. Xi Jianxi accepted her due to a System mission, raised her for two years before the Holy Grail War, and supported her decision to pursue advanced magecraft studies. 1 2 48
• Kallen Ostia (Karen) — Adoptive younger daughter, entrusted to Xi Jianxi by Kirei Kotomine. Xi Jianxi placed protective runes on her because of her constitution’s reaction to spirits. 18 23
• Scathach — Master who trained him in the Shadow Realm and left him his Noble Phantasm. She later intervened when his plant-growing research touched upon divine authority. 2 22 48
• Kirei Kotomine — Former acquaintance and Kallen’s biological father. Xi Jianxi adopted Kallen out of their prior connection but refuses to use her as leverage against Kirei. 18
• Tokiomi Tohsaka — Sakura’s biological father, who entrusted Sakura’s magical education and guardianship to Xi Jianxi. 1
• Artoria Pendragon — Temporary ally during the Holy Grail War. They fought Caster and Gilgamesh together, with Xi Jianxi affirming his faith that Morgan would not betray her. 15 39 40
• Irisviel von Einzbern — Allied with Xi Jianxi to suppress Caster, motivated in part by their shared concern for children endangered by the war. 14
• Lord El-Melloi II — Formerly Waver Velvet. After the war, he sought Xi Jianxi’s help as tutor to the El-Melloi successor. 48
• Leinette El-Melloi Arch Zolti — Xi Jianxi’s private student and the El-Melloi heir; she hired him despite his killing of Kayneth, prioritizing his skill over revenge. 49

Story Role / Major Arcs

Shadow Realm and Fuyuki Family

• Survives the Shadow Realm, meets its Queen, and receives a new destiny. 1
• Becomes Scathach’s disciple and gains the combat and rune skills that define his fighting style. 2
• Adopts Kallen, then Sakura, and establishes a family home and workshop in Fuyuki. 1 2

Fuyuki Holy Grail War

• Receives Command Spells against his will and summons Fairy Queen Morgan instead of the Berserker he expected. 2 3
• Battles Diarmuid directly, revealing strength and rune magecraft sufficient to contend with a Servant. 7 9
• Confronts Gilgamesh, using King’s Pawn, spatial movement, and the Demon Spear to survive a barrage of Noble Phantasms. 10 11
• Forms a temporary alliance with Irisviel and Artoria to eliminate Caster, primarily to keep Fuyuki’s children—including his daughters—safe. 14 15
• Saves the final surviving child used by Caster as a sacrifice by placing him into deep sleep. 15
• Defeats Kayneth El-Melloi Archibald after breaking through his twenty-four magical barriers, familiars, Mercury Dress, and ice magecraft. 20 21
• Helps organize cooperation among the remaining Masters after learning the Greater Holy Grail is corrupted. 29
• Defeats Hassan of the Hundred Faces’ divided bodies and identifies the Assassin’s true identity. 34 35
• Joins Artoria and Iskandar against Gilgamesh, ultimately using Gae Bolg Alternative to pierce Gilgamesh’s spiritual core. 44
• Protects Morgan from Justicia, confronts the Black Grail’s manifestation, and helps destroy it before Morgan purifies the Greater Holy Grail. 45 46

Post-War Life

• Forms a new contract with Morgan rather than allowing her to disappear after the Holy Grail War. 46
• Continues research in the Shadow Realm, eventually growing an apple tree in its lifeless terrain at the cost of collapsing from overexertion. 48
• Sends Sakura to the Clock Tower for advanced magecraft courses and becomes Leinette El-Melloi Arch Zolti’s private tutor. 48 49
• Travels with Morgan to Wales and Blackmore Cemetery to investigate a place connected to her past and the “Black Madonna.” 49 50

Trivia

• Xi Jianxi’s System gives him missions and punishments without reliably explaining their rewards; he openly considers it crueler than slavery. 1
• He frequently oversleeps on days off, a habit Sakura has learned to exploit when presenting completed magecraft homework. 2
• He is capable of cooking and managing housework, regularly preparing meals for Sakura and Kallen and hosting an improvised banquet for several Holy Grail War participants. 4 24
• Morgan considers Xi Jianxi’s workshop unusually warm and human compared with a typical magus’s workshop. 24