Mayumi Saegusa

Biodata

Power Progression

Mayumi’s documented development consists of new techniques and equipment rather than named cultivation realms or personal rank promotions.

Background

Mayumi is the eldest daughter of the Saegusa Family, one of the two families described as the pillars of the Ten Master Clans alongside the Yotsuba Family. Her position makes her marriage a political concern: Koichi expects a partner from the Ten Master Clans or, at minimum, the Assistant Eighteen Houses 14 40 55.

At First High School, her presidency places her between the increasingly antagonistic Course 1 and Course 2 students. Although her family name gives her considerable authority, she recognizes that invoking it to settle a school dispute would undermine her role as student council president 4.

Appearance

• Build: Petite, with a cute face; Yunyi considers her beauty comparable to Miyuki Shiba’s and Lina’s 1.
• Eyes: Wine-red, also described as burgundy 30 62.
• Competition equipment: Carries a rifle-shaped CAD and wears protective goggles for Speed Shooting 71.
• Mirage Bat outfit: Wears a dress chosen as part of a matching outfit with Yunyi, giving it personal significance beyond its appearance 110.

Personality

Mayumi is socially perceptive and capable of adapting her approach under pressure. When Yunyi challenges whether she is intervening as president or as a Saegusa, she instead speaks as a fellow student proposing a mutually beneficial resolution. She also notices inconsistencies in his behavior and eventually concludes that much of his public identity is an act 4 24.

She enjoys teasing others, but becomes easily flustered when Mari or Yunyi turns that teasing back on her. As her relationship with Yunyi develops, she becomes more openly affectionate and increasingly willing to act without the restraint expected of a Saegusa daughter 22 42 63 71.

Her independence does not eliminate her sense of responsibility. She prioritizes the twins’ safety while detained by Yunyi, remains at the estate to support her family during the Ogasawara crisis, and later seeks protection for her sisters before a possible departure from Japan 20 164 244.

Mayumi knowingly chooses Yunyi despite their opposing national and political positions. She supports his ideas for the future, but still objects when his plans endanger people close to her, particularly Mari 82 123 175.

Abilities & Skills

Magic Bullet Shooter

Mayumi’s Speed Shooting magic creates dry-ice projectiles from air, maintains their state, and accelerates them to subsonic speed 71.

• Achieves perfect scores through the preliminaries, quarterfinals, and semifinals of the Nine Schools Competition 72.
• Destroys three designated targets almost simultaneously at the start of the final 72.
• Inspires Yunyi’s Sky-Splitting Magic Bullet, although his version uses compressed air and substantially greater destructive force 84.

Double-Speed Rebound

A spell Mayumi is particularly skilled at using in Crowd Ball 46.

• Helps her win a practice match against another third-year competitor by an overwhelming margin 46.
• Shares characteristics with Yunyi’s Mirror Reflection, but has a lower vector limit 46.

Line-of-Sight Magic and Psion Control

Mayumi specializes in line-of-sight magic and is proficient enough at Psion control for Yunyi to consider her well suited to his vector-based flight technique 16 92.

• Attempts to use her specialty after taking cover during the department-store attack 16.
• Her active magic is forcibly terminated when Yunyi’s Fool’s World takes control of the surrounding Psions 16.
• Within his domain, she also loses access to the Psions inside her own body 17.

Flight-Like Compound Magic

Yunyi prepares a simplified technique for Mayumi’s participation in Mirage Bat, supported by a CAD adjusted by Tatsuya 88 92 108.

• Weight elimination: Makes her movements light and slows her descent, but does not remove gravity’s effect 92 108.
• Vector application: Propels her in chosen directions; she controls the speed and distance of each dash 92.
• Loop Cast: Repeatedly applies vectors, allowing her to remain airborne while moving between targets 108.
• Advantages: Low Psion consumption and faster short-distance acceleration than general-purpose Flight Magic 108 111.
• Limitations: The original, stronger vector spell is unsuitable for her physically delicate body. More advanced versions of Yunyi’s flight magic require his unique Domain Magic 59 92.

Engraving-Type Casting

Mayumi’s custom CAD contains engraved spell components that activate when supplied with Psions 197 198.

• Allows her to use stored magic without knowing its Activation Sequence 198.
• Includes some techniques previously used by Yunyi 198.
• Produces an almost instantaneous attack powerful enough to pierce an executor, surprising both Mayumi and Lina 230.

Leadership and Diplomacy

Mayumi’s standing among First High’s students makes her particularly effective at managing public incidents 33.

• Negotiates an auditorium debate with the Alliance of Volunteers over the Course 1–Course 2 conflict 29.
• Quickly calms the auditorium after a terrorist attack 33.
• Handles competition arrangements, participant checks, room assignments, and preparations for the Student Council succession 56 62 63 116 130.
• Later coordinates with Yunyi in negotiations intended to recruit Tatsuya and Miyuki 307.

Cooking

• Prepares a substantial breakfast that Yunyi praises and finishes completely 42.
• Shares responsibility for cooking for Kasumi and Izumi while balancing Student Council work 130.

Equipment / Items

• Wrist-worn CAD — Visible during her mediation of Yunyi’s confrontation with Shun Morisaki 4.
• Rifle-shaped CAD — Used in Speed Shooting 71.
• Mirage Bat CAD — Adjusted by Tatsuya to support Yunyi’s prepared flight-like spell 92 108.
• Custom Engraving-Type CAD — A compact wrist-worn model specially made by Shen Yi; later becomes central to Mayumi’s defense of the mansion 197 198 230.
• Personal terminal — Used for news, competition records, participant lists, and communications 16 62 116.

Relationships

• Yunyi — Initially a suspicious newcomer whose secrets place Mayumi and her sisters in danger. Their pretend romance develops into a genuine relationship, cohabitation, and political partnership 20 24 44 61 118 307.
• Koichi Saegusa — Her father and the Saegusa Family head. Initially evaluates Yunyi as a potential marriage partner, later accepts their relationship, and considers entrusting the family to Mayumi 55 117 142 310.
• Sachiko Saegusagawa / Mrs. Saegusa — Her mother. Worries about Mayumi’s future with Yunyi and urges her to gain the resources and authority needed to protect her position 141 175.
• Kasumi Saegusa — Younger sister. Mayumi protects her, helps supervise her magic practice, and eventually tells Yunyi that Kasumi has fallen in love with him 20 151 270.
• Izumi Saegusa — Younger sister and Kasumi’s twin. Lives with Mayumi at Yunyi’s home; Mayumi later gives both twins their promised Engraving-Type CADs 118 266.
• Mari Watanabe — Close friend and fellow school leader. Frequently teases Mayumi about Yunyi; Mari’s injury creates a serious disagreement between the couple 22 69 82 87.
• Suzune Ichihara — Student Council colleague whom Mayumi calls “Rin.” Helps manage competition strategy and notices when Mayumi’s behavior is unusual 20 22 70 203.
• Katsuto Jumonji — Friend and fellow member of the Ten Master Clans. Their cooperation becomes strained when he objects to her choices in his capacity as family head 107 126.
• Tatsuya Shiba — Student whose combat skills she accepts as sufficient for Public Morals Committee work; later tunes her Mirage Bat CAD and becomes a target of her recruitment efforts with Yunyi 12 108 307.
• Miyuki Shiba — Recruited by Mayumi into the Student Council. Agrees to Mayumi replacing Mari in Mirage Bat rather than taking the main-event place herself 7 83.
• Lina — Cooperates with Mayumi in defending the mansion and is astonished by the speed of her Engraving-Type attack 230.
• Shen Yi — Approves of Mayumi during their first meeting and later gives her the custom Engraving-Type CAD 124 197.

Story Role / Major Arcs

Enrollment and the Course Conflict

Mayumi first appears offering help to new students. She later persuades Yunyi to release Shun Morisaki by approaching him as a fellow student rather than relying on either her presidency or family status 1 4.

She recruits Miyuki into the Student Council, although school rules prevent Miyuki’s preferred candidate, Tatsuya, from joining as a Course 2 student. Mayumi subsequently helps arrange an assessment of Tatsuya for the Public Morals Committee 7 10 12.

Department-Store Attack and Yunyi’s Identity

An armed attack places Mayumi, Kasumi, and Izumi in danger. Yunyi protects them and reveals Domain Magic, demonstrating that his abilities far exceed his public claims. Mayumi questions his identity and purpose, fearing the implications of becoming his enemy 15 16.

Yunyi then holds the sisters for more than ten hours before releasing them. Mayumi cooperates out of concern for the twins and conceals what happened from Suzune afterward 20.

Her suspicion does not disappear. She investigates Yunyi’s motives, learns that he is a Great Asian Alliance second lieutenant codenamed The Fool, and eventually receives assurances that he will protect First High’s students during the coming debate 24 29 30.

Debate and Terrorist Attack

Mayumi negotiates a public debate with the Alliance of Volunteers and helps position Mari and Katsuto around the school. When attackers disrupt the auditorium, Yunyi defeats them and Mayumi restores order among the frightened students 29 32 33.

She insists on accompanying the operation against the terrorists’ base despite Mari’s objections. Afterward, she carefully answers Koichi’s questions while withholding sensitive information about Yunyi 36 39.

Pretend Romance Becomes Genuine

Pressure over her marriage prospects leads Mayumi to arrange a pretend relationship with Yunyi. She proposes using his Nine Schools Competition performance to demonstrate enough value to persuade her father 40 42 44.

Their repeated arrivals at school attract widespread attention. Yunyi publicly takes her hand and announces that they are together, while Koichi grants her until graduation to prove the relationship worthwhile 49 55.

The arrangement becomes emotionally genuine as Mayumi confides her fears about their future. She cries in Yunyi’s arms, kisses the corner of his mouth, and later deliberately initiates another kiss rather than acting only on impulse 61 64.

Nine Schools Competition

Mayumi competes while helping organize First High’s team and adjusting to unexpected losses and Mari’s injury. Her disagreement with Yunyi over his decision to endanger Mari becomes their first quarrel, though they reconcile 70 71 82 83.

After the competition, Koichi withdraws his opposition to Yunyi. Mayumi requests permission to live with him, and Koichi agrees; Kasumi and Izumi are also sent to stay there 117 118.

Family Pressure and Choosing Her Future

As Mayumi prepares to hand over Student Council duties, Katsuto formally challenges her decision. She refuses to reverse it and directs any clan objection through official correspondence with the Saegusa Family 126 130.

Koichi later promises not to oppose the relationship even when Yunyi’s hidden background threatens to become public. Mayumi’s mother urges her to seek the family headship, both to support Yunyi and to secure her own position. Mayumi considers the proposal, but no completed succession is documented 142 175 176 310.

Mansion Defense and Departure from Japan

During the Parasite crisis, Mayumi helps monitor intelligence and later works with Lina to defend the mansion. She places the twins in the guest room, uses darkness to draw the attackers into action, and unleashes her Engraving-Type spell against an executor 217 230.

As military tensions rise, she warns Katsuto about a possible American naval approach and confirms Yunyi’s alignment with the Great Asian Alliance. Knowing that disclosure may force a choice between him and the Ten Master Clans, she asks him to protect her sisters if they must leave Japan 244.

Mayumi leaves Japan with Yunyi. First High’s remaining leaders discuss her departure as a defection rather than merely the loss of a Saegusa daughter 271.

Wartime Negotiations and Return

Mayumi proposes another attempt to recruit Tatsuya and Miyuki. She and Yunyi plan complementary roles: he applies pressure, while she intervenes to offer hope. During the talks, she identifies herself as having left the Saegusa Family but insists that she does not want her homeland devastated by war 307.

She later returns to the Saegusa residence with Yunyi and the twins. Her family learns more about his overseas authority, while Koichi expresses willingness to entrust the family to her without claiming that this would automatically secure the other clans’ support 309 310.

When Japan faces invasion, Mayumi continues to interpret the political motives of visitors around Yunyi, explaining that Kyoko Fujibayashi has come to assess whether he intends retaliation against the Fujibayashi Family 322.

Notable Quotes

“No, I'm speaking neither as the student council president nor as a daughter of the Saegusa Family. I'm simply a student of First High School making you a proposal that would benefit both of us.” 4

“I don't want to become your enemy.” 16

“I believe in him. As long as we keep going, we have hope of bringing about that kind of future. This isn't just for ourselves, Mari. It's for the future too.” 123

“At first, I only wanted to escape the fate of a political marriage, but I chose him myself, knowing who he was.” 175