Miyuki Shiba

Biodata

Background

Miyuki is the biological daughter of Tatsurou Shiba and Miya Yotsuba. After confirming that she had inherited her mother's Non-Systematic Magic, the Yotsuba Clan altered her DNA. Yunyi describes her as an exceptionally perfected adjusted human, while explicitly distinguishing her from an artificial human 169.

Her upbringing was tied to the clan's control of Tatsuya. Miya and Maya subjected him to an artificial-magician operation that erased nearly all his emotions except those directed toward Miyuki, then assigned him as her guardian. Miyuki consequently became both his central emotional attachment and a restraint on his power 169.

Yunyi further reveals that Miyuki's adjustments made her suitable to marry Tatsuya and bear his children. Maya later confirms the truth of his revelations to Tatsuya 169 182.

Personality

Miyuki centers much of her life on Tatsuya. She takes pride in his technical abilities, defends his qualifications, and seeks opportunities for others to recognize him. When invited into the Student Council, she first argues that her brother would be the better recruit; she subsequently recommends him for the Public Morals Committee 7 8 27.

Her deference to him does not eliminate her competitive streak. She actively seeks a match against Yunyi and remains dissatisfied after losing, wanting to understand his magic rather than dismissing the result as carelessness. She also pursues control training partly to overcome his criticism that she is clumsy with precise spellwork 46 50 54 207.

Miyuki is perceptive despite her sheltered outlook. She recognizes that Yunyi's assessment of Lina implies an unusual hidden identity, and later argues that his increasingly open behavior reflects confidence that Japanese magicians cannot threaten him. Nevertheless, the responsibility of directing the Yotsuba Clan leaves her visibly overwhelmed, and Maya considers her hopes for peace during the invasion naive 200 253 259 290.

Her attitude toward Yunyi develops from resentment into guarded hope. Although his teasing and interference frustrate her, she notices that Tatsuya displays previously absent expressions around him. Restoring her brother's emotional life becomes a reason to continue seeking Yunyi's help 208 327.

Abilities & Skills

Deceleration Magic

Deceleration is Miyuki's specialty, supported by magical talent regarded as among the best of the Yotsuba succession candidates 46.

• Freezing: She can freeze a glass of water almost immediately 133.
• Precision limitation: During training, she repeatedly freezes the entire glass instead of isolating half its contents, demonstrating a gap between her power and fine control 127 133.
• Training approach: Yunyi instructs her to solidify only half the liquid while leaving the other half unaffected, using a small target before attempting larger spells 127.

Inferno / Ice Flame Hell

Miyuki uses the A-rank spell Inferno through an Activation Sequence prepared by Tatsuya. During her spar with Yunyi, it covers her half of the field in intense cold and his half in scorching heat 50.

• Icicle Destruction: The temperature contrast protects her side while attacking opposing icicles 50 90.
• Combination tactics: Against Shizuku, she switches from Niflheim to Ice Flame Hell, using Inferno's heat to vaporize condensed liquid nitrogen and destroy the opposing icicles through rapid expansion 91.
• Demonstrated counter: Yunyi's Frozen Shadow preserves his icicles against Inferno; Black Rope Hell subsequently overwhelms the cold defending hers 50 51.

Niflheim

Miyuki uses Niflheim during her Nine Schools Competition match against Shizuku. Its cooling effect condenses liquid nitrogen on Shizuku's side, creating the conditions for Miyuki's finishing combination with Inferno 91.

Zone Interference

The large quantity of Psions accompanying Miyuki's spell construction interferes with nearby opponents' magic 50 122.

• Slows Yunyi's unfolding Activation Sequence during their spar, giving Miyuki the initiative 50.
• Disrupts Shizuku during contests to rewrite a target's information 122.
• Can be countered through concentrated magic and selective reinforcement: with Yunyi's guidance, Shizuku protects part of the target before reclaiming the rest 122.

Mental Interference Magic

Miyuki is proficient in mental magic and assists Yunyi against the Parasites 170 221.

• Parasite interference: Using the perception provided by Yunyi's magic, she targets the separate vital signs inside Kanon Chiyoda. The Parasite reacts by attempting to escape its host 222.
• Direct Pain: She and Yuuka Tsukuba use Mental Interference Magic to suppress the gathered Parasites, but the combined entity formed from thirty-one Parasites resists and counterattacks 228.
• Induced sleep: She puts Tatsuya to sleep without harming him, avoiding the automatic activation of his self-repair. His willpower allows him to awaken earlier than she expects 232.

Cocytus and the Contract

Miyuki possesses Cocytus, but its use is restricted by the arrangement sealing Tatsuya's abilities 228.

• She must undo the seal on Tatsuya before using the spell 228.
• During the Parasite hunt, she cannot employ it because she did not release the seal beforehand 228.
• The siblings' contract also allows Tatsuya to sense her location 232.

Spellcasting and Resistance

• Kotodama resistance: Tatsuya confirms that Miyuki shares his resistance to the direct action-control effect Yunyi describes. However, Yunyi successfully influences a group including Miyuki through much subtler conversational suggestion 8 12.
• Casting without an Activation Sequence: She can do so, but the spells available to her that way are insufficient to resolve her predicament against Yunyi during their spar 50.
• Dependence on Psion access: Her attempted Flight Magic fails inside Yunyi's Fool's World, which prevents her magic from taking effect 293.

Equipment / Items

• CAD — Adjusted by Tatsuya, who also prepares her Inferno Activation Sequence. Her available stored sequences limit her responses during the spar against Yunyi 50 53 68.
• Rings delivered by Yunyi — After receiving a private message from him, Miyuki takes the rings from Tatsuya and places one on his finger. She acts out of eagerness for her brother's recovery; the passage does not establish the resulting effect 327.

Story Role / Major Arcs

Enrollment and Student Council Recruitment

Miyuki enters First High School as the freshman representative and a Course 1 student. Her association with Tatsuya and his Course 2 friends attracts unwanted interference from Course 1 students, including Shun Morisaki's group 2 7.

Mayumi invites her to join the Student Council. Miyuki initially advocates recruiting Tatsuya instead, but accepts after learning that school regulations restrict membership to Course 1 students. She then proposes him for the Public Morals Committee, leading to an assessment of his abilities 7 8.

Nine Schools Competition

Miyuki qualifies for automatic entry to the competition trials because of her entrance-exam standing, but visits the simulation grounds to challenge Yunyi. Her determination to win persuades Tatsuya to permit the match 50.

Miyuki also agrees to help persuade Tatsuya to lead First High School's replacement Monolith Code team. At the closing ball, she dances with Masaki Ichijo, Yunyi, and Tatsuya, thanking Yunyi for his earlier advice to the siblings 93 114 115.

Magic-Control Training

After Shizuku defeats her in a practical exercise under Yunyi's direct guidance, Miyuki joins Shizuku and Honoka in seeking instruction on concentrating magic. Her exercises expose difficulty controlling a small portion of a target without affecting the whole 122 127 133.

A later lesson ends when she withdraws from Yunyi's hands-on guidance. Despite their friction, she continues practicing and eventually asks him to assess her progress, increasingly viewing his unconventional approach as a possible route to a different future for herself and Tatsuya 133 207 208.

Yotsuba Orders and Succession

Maya orders Miyuki to establish a closer relationship with Yunyi while forbidding hostility. Yunyi interprets the order as a trap that could compromise the siblings, but Maya later denies having originally intended to marry Miyuki to him 158 161 181.

After Miyuki privately asks Yunyi about her relationship with Tatsuya, his disclosures force the siblings to confront the clan's alterations to their lives. Their subsequent meeting with Maya brings both a new political role for Miyuki and a private engagement 169 182.

To make the engagement publicly acceptable, Maya announces Tatsuya as her own son, supposedly conceived through artificial insemination using a frozen egg. This is a constructed lineage: Miyuki and Tatsuya remain biological siblings 169 182 313.

Parasite Crisis

Miyuki volunteers to help Yunyi while asking him to keep Tatsuya out of the operation. She assists with the Parasite inside Kanon and later participates in the hunt alongside Yuuka 221 222 228.

To leave without involving her brother, she puts him to sleep. The operation becomes more dangerous when the Parasites merge, overpowering the pair's suppression magic. Because Tatsuya's seal remains in place, Miyuki cannot use Cocytus 228 232.

War and Abduction

Miyuki and Maya privately agree to try to prevent Tatsuya and Yunyi from facing each other on the battlefield. That effort fails to preserve their former relationship: after declaring Tatsuya an enemy, Yunyi disables the siblings' magic and abducts Miyuki 286 293 294.

Yunyi takes her to an isolated Pacific island and demands that Tatsuya destroy everyone connected to the Itsuwa Family in exchange for her release. Miyuki asks him to leave the siblings alone, but he argues that Tatsuya's power makes withdrawal from conflict impossible. During captivity, her freedom is restricted, though her daily living conditions otherwise remain ordinary 294 296.

By the hospital visit involving Masaki, Miyuki is back with Tatsuya; the provided account does not describe her release. Information she obtains while away contributes to their understanding that Yunyi has support within the Union and overseas 304.

Negotiations and Tatsuya's Recovery

Miyuki and Tatsuya seek a meeting with Yunyi to learn what changes he intends to impose on the world order. Later, he offers a way to restore some of Tatsuya's other emotions while preserving Miyuki as his unique special attachment, leaving the siblings to propose adequate compensation 304 320.

When Yunyi subsequently delivers rings, Miyuki immediately places one on Tatsuya's finger after hearing Yunyi's message in her mind. Her eagerness reflects her foremost wish: her brother's recovery 327.

Relationships

• Tatsuya Shiba / Tatsuya Yotsuba — Biological elder brother, guardian, and fiancé. Their bond is both deeply personal and deliberately engineered by the Yotsuba Clan; Miyuki actively seeks the restoration of his suppressed emotions 169 182 313 327.
• Maya Yotsuba — Aunt and family head. Initially an intimidating authority, she appoints Miyuki acting head and progressively transfers genuine decision-making power to her 158 181 182 259 312.
• Miya Yotsuba — Mother and source of Miyuki's inherited Non-Systematic Magic. She participates with Maya in the operation that leaves Tatsuya emotionally bound to Miyuki 169.
• Yunyi — Classmate, opponent, and magic-control instructor whose relationship with Miyuki alternates between cooperation, resentment, hope, and coercion. He exposes the siblings' origins, later abducts her, and ultimately offers help with Tatsuya's emotions 133 169 208 294 320.
• Mayumi Saegusa — Student Council president who recruits Miyuki and later advises her to tell Tatsuya before taking similar risks again 7 236.
• Shizuku Kitayama — Friend, competition rival, and fellow magic-control trainee. Their Icicle Destruction match ends in Miyuki's narrow victory 91 127 146 207.
• Honoka Mitsui — Friend and fellow trainee, regularly accompanying Miyuki and Shizuku at school 127 201 206 207.
• Yuuka Tsukuba — Fellow Yotsuba mental magician whom Miyuki recommends for Yunyi's assessment and later works alongside against the Parasites 193 221 228.
• Masaki Ichijo — Invites Miyuki to dance at the competition ball and later asks to join the siblings' proposed meeting with Yunyi 114 304.