Jack

Biodata

Feature	Information
Name	Jack (杰克)
Alias(es)	Jack the Ripper; Little Jack
Species/Race	Heroic Spirit; a collective of infants who were never permitted to be born
Gender	Female
Affiliation	Yuxian's group; Chaldea
Occupation/Role	Assassin-class Heroic Spirit; Yuxian's adopted daughter
First Appearance	Chapter 13

Background / History

Jack first reunites with Yuxian after rushing from an abandoned building into his arms and calling him “Mama.” Though Yuxian is male, he accepts the title because Jack sees him as the motherly figure she had always lacked. Her true nature is a collective of unborn, abandoned children rather than an ordinary Cursed Child. 13 14

Initially, Jack reacts to threats against Yuxian with immediate lethal force. She silently places a dagger at Hiruko Kohina's throat, but withdraws when Yuxian reminds her that Kohina is also a child. 15 When she discovers surveillance on Yuxian's home and overhears an order to eliminate the household, she kills the spy and later assassins Kikunojo Tendo. 18 19

After Kikunojo's death, Yuxian explains that she must tell him before acting alone. Jack accepts this guidance, though protecting “Mama” remains her highest priority. 20 School, friendships, games, and ordinary family life gradually soften her behavior; Yuxian notes that she has become more obedient and better able to adapt to normal life. 35

Yuxian gives Jack a birthday shared with his own, recognizing that she had never been born and therefore had never had one. Jack becomes intensely excited by the celebration and later treats the date as something precious. 36 67

During the confrontation with Hero Killer Stain, Jack nearly returns to her old brutality after Stain attacks Yuxian. When Yuxian stops her, she cries for the first time and reveals her fear that she is useless because she cannot always protect him. 64 65

In London, Jack intervenes to protect an injured woman from a Magus, then uses her surgical knowledge to stop the woman's bleeding and stitch her wounds. This marks a major reversal of the skills once associated with the Ripper: she uses them to save rather than kill. 125 126 She later rejects London as her homeland, declaring that her true home is wherever Yuxian is. 139

Jack successfully summons King Hassan and quickly forms a grandfather-granddaughter bond with him. Though he offers to train her as a proper assassin, she declines because Yuxian has told her she no longer needs to kill. 150 152

Appearance

Jack is a small girl with a childish face, large bright eyes, and an outwardly innocent smile that contrasts sharply with her combat methods. 18 19

• Often wears cute clothes or pajamas chosen by Yuxian. 18 19
• Uses a ragged, hole-ridden cloak when she expects combat, so her nicer clothes will not get dirty. 18
• Carries small daggers, usually held in a reverse grip. 15 19
• Can appear suddenly behind opponents without being noticed. 15

Personality

Jack is affectionate, straightforward, and deeply dependent on Yuxian, whom she consistently calls “Mama.” Her concept of family is central to her identity; she considers being without a mother deeply pitiable because of her own past. 18 139 197

Her morality is initially very different from that of ordinary children. She sees anyone who threatens Yuxian as someone who must be killed, and she can discuss dismemberment with complete innocence. 15 18 137 However, she is highly receptive to Yuxian's guidance and gradually learns restraint, apology, and concern for others. 20 54 126

Despite her assassin nature, Jack is playful and curious. She enjoys hide-and-seek, fighting games, chasing rivals, observing animals, and treating dangerous situations as games. 36 39 150 179 195 She can also be cunning when needed, such as downplaying the children's activities to Yuxian without technically lying. 76 99

Abilities & Skills

Presence Concealment

Jack possesses Presence Concealment A+, allowing her to erase her presence so thoroughly that ordinary people, surveillance equipment, and even skilled opponents struggle to detect her. 15 68

• Can approach targets from behind without alerting them. 15 18
• Moves silently and rapidly through urban environments, especially at night. 18
• Can evade detection during training exercises even when opponents actively search for her. 68
• Her concealment is most effective when she is not attacking. 68
• King Hassan can still locate her through experience and observation. 150 152

Dagger Combat

Jack is an extremely fast close-quarters fighter who uses paired daggers with lethal precision. 19 25

• Can fight Initiator Hiruko Kohina evenly while deliberately withholding her skills and Noble Phantasms. 25
• Redirects the Arrow Demon's projectiles by striking them with her daggers, despite being unable to cut them. 195
• Her speed and agility surpass Tanjiro's expectations during their encounter with demons. 195
• Often restrains herself after Yuxian's guidance instead of immediately killing opponents. 54 64

The Mist

The Mist is a Noble Phantasm that creates a magical fog barrier modeled after London's historical “fog of death.” 19

• Damages those trapped inside and disrupts their sense of direction. 19
• Conceals Jack's movements and makes locating her exceptionally difficult. 19 64
• Allowed her to isolate and kill Kikunojo Tendo. 19
• Was used against Stain, enabling Jack to inflict numerous wounds before Yuxian called her back. 64

Maria the Ripper

Maria the Ripper imbues Jack's four daggers with the resentment of unborn children and enables a rapid, multi-directional slaughter within the fog. 19

• Its power rises when three conditions are met: night, fog, and a female target. 19
• When all three conditions are fulfilled, it becomes a curse capable of activation from a distance. 19
• Jack used it at night within The Mist to kill Kikunojo Tendo, though the target was male and the Noble Phantasm was therefore not at full power. 19

Surgical Knowledge

Jack possesses considerable surgical experience intrinsic to her identity as Jack the Ripper. 126

• Stopped an injured woman's bleeding and stitched her wounds after protecting her from a Magus. 126
• Represents a major change from her earlier use of blades solely for killing. 126

Equipment / Items

• Daggers — Jack's primary weapons; used for stealth attacks, close combat, and Noble Phantasms. 15 19
• Tattered cloak — Old combat clothing worn to avoid staining her nicer outfits. 18
• Book of Curse Arts — Given to her by Fafnir, who was interested in her dark aura. 49

Relationships

• Yuxian — Her Master and adoptive mother figure. Jack's strongest desire is to remain with him forever, and she becomes distraught when she believes she cannot protect him. 18 36 64 65
• Gretel — Close friend who worries about Jack's recklessness, defends her when others mock her, and helps keep her actions in check. 52 64 126
• King Hassan — Summoned Servant and grandfather figure. He plays hide-and-seek with Jack and offers to teach her assassination, which she declines. 150 152
• Kohina Hiruko — Initially threatened by Jack, later becomes a schoolmate and sparring partner. Kohina is interested in Jack and seeks matches with her. 15 16 25
• Kanna — Beach companion who joins Jack in observing and trying to catch a crab. 39
• Karna and Arjuna — Referred to as Jack's fathers during the fan-meeting incident; both show concern when she jumps from the venue ceiling. 282 283
• Berserker Jack — Another manifestation of Jack the Ripper. The two share an immediate sense of familiarity and meet during the Snowfield Holy Grail War. 336 339

Story Role / Major Arcs

• Tokyo Area — Defends Yuxian's household from Kikunojo Tendo's agents and assassinates Kikunojo after identifying him as the threat. 18 19
• School Life — Attends school, befriends Kohina, follows Tina Sprinter on Yuxian's orders, and prevents Hina from carrying out a killing. 23 25
• Musutafu / Stain Incident — Pursues Izuku Midoriya, severely wounds Stain after he threatens Yuxian, and confronts her own fear of being useless. 64 65
• London and the Eyeball Collection Train — Saves an injured woman, demonstrates surgical skill, and faces the emotional weight of London's connection to Jack the Ripper. 125 126 139
• Servant Summoning — Summons King Hassan, gaining a patient mentor and playmate. 150 152
• Snowfield Holy Grail War — Meets Berserker Jack and intervenes to rescue him after Alcides defeats him. 336 339

Notable Quotes

“We’re Jack.” 16

“Our homeland is where Mom is!” 139

“But Mom said Jack doesn't need to kill anyone anymore.” 152

Trivia

• Jack shares her birthday with Yuxian because she had never possessed one of her own. 36
• She loves hide-and-seek, but her Presence Concealment usually makes the game too easy unless she deliberately leaves clues. 150
• Jack drew the flag for the group's ship, Chaldea. 51
• She received applause after performing in a Christmas play and realized that people beyond Yuxian and Gretel could welcome and like her. 45