Mayumi Saegusa

Biodata

Power Progression

Mayumi’s documented performance improvements come from Chiba Yeyou’s CAD adjustments and enhancements.

Background / History

Family and School Position

Mayumi is described as the Saegusa Family’s youngest daughter and “little princess.” Her family belongs to the Ten Master Clans. At First High School, she serves as the elected Student Council President during her third year 2 16 18.

Her office gives her responsibility for selecting and dismissing Student Council members and, with exceptions, appointing committee chairs. The Public Morals Committee chairmanship falls outside that authority because its members elect their own chair 18.

Recruiting Chiba Yeyou

Mayumi meets Chiba Yeyou at the beginning of his first year. After noticing unusual magic that he has switched off, she invites him to become her personal secretary. When Hattori objects that the appointment violates recruitment rules, she offers to hire Yeyou personally and refuses to reverse her decision 2 4 5.

Their conspicuously intimate conversation starts widespread school gossip. Mayumi initially uses the prospect of rumors to coax him into accepting, but becomes embarrassed and angry when students invent stories about an engagement, a childhood romance, and an overnight visit 5 6.

Course 1–Course 2 Dispute

Mayumi inherits an increasingly bitter division between Course 1 and Course 2 students. She hopes that Yeyou’s indifference to the distinction, together with the arrival of Tatsuya and Miyuki Shiba, can help ease the conflict 17.

She persuades Mari Watanabe to treat an early confrontation as a misunderstanding. Later, she recruits Miyuki as a Student Council secretary and supports offering Tatsuya and Erika Chiba positions on the Public Morals Committee, which has no Course 1 membership requirement 12 18.

When the dispute escalates around Sayaka Mibu’s group, Mayumi asks that the students be released so negotiations can proceed. She chooses to represent the Student Council alone in the public discussion, reasoning that a single speaker will avoid inconsistencies. Although confident in her debating ability, she states that persuasive demands could be incorporated into school policy 45 46.

During the discussion, she defends club funding as results-based rather than course-based. She also rejects replacing existing inequality with new discriminatory treatment and draws attention to the Student Council’s own unequal membership rule 49.

Nine Schools Competition

Mayumi coordinates First High’s preparations with Katsuto Jumonji and identifies a shortage of maintenance engineers. Remembering that Yeyou adjusts his own CAD, she recommends him and Tatsuya for technical support and arranges a practical test of their skills 55 58.

As a competitor, she enters Speed Shooting and Crowd Ball. Yeyou’s tuning produces decisive victories in both events, surprising spectators and students familiar with her previous performances. After the Speed Shooting match, she and Mari ask him to calibrate their personal CADs as well 62 80 83 84.

Her administrative responsibilities continue throughout the tournament. She helps assess First High’s overall scoring prospects and participates in discussions after the Monolith Code competitors are injured. The group suspects interference through CAD inspections, but Yeyou cautions her against confronting Fourth High without evidence 90 115 117.

When Yeyou’s abilities attract outside investigation, Mayumi offers him her support and privately orders an aide to warn interested factions. She later sends protection after him when he and Tatsuya leave to confront No Head Dragon’s Japanese leadership 123 134 135 137.

At the competition’s conclusion, Yeyou briefly shares the sensory view of Quantum Domain with her. She witnesses its numerical representation of magical power, while he clarifies that it cannot expose Phalanx’s deeper workings. She stays beside him during the awards ceremony and dances with him at the interschool social 139.

Hachioji and Yokohama

Mayumi joins Yeyou in questioning Isao Sekimoto at the Hachioji Special Juvenile Detention Center. Sekimoto reveals that his group intended to search Tatsuya’s belongings for a Relic 150.

During the Yokohama attack, Yeyou catches Mayumi as she rushes forward and stops her from casting, warning her against exposing herself to high-velocity gunfire. Later, she reports that a rescue ship will arrive in ten minutes but cannot accommodate everyone, prompting discussion of sheltering at the station instead 156 158.

Appearance

• Build: Petite and short; comments about her height repeatedly irritate her 2 16 123.
• Hair: Long enough to flutter over her shoulders while she runs 16.
• Complexion: Fair skin, noted during her early interactions with Yeyou 2.
• Clothing: Wears an orange-yellow skirt during one morning walk to school, and a white dress with a white sun hat before her Crowd Ball preliminary 16 83.

Personality

Mayumi enjoys teasing her juniors and has a mischievous reputation among her friends. Her composure frequently falters when Yeyou turns the teasing back on her: she blushes, pouts, retaliates with pinches or light blows, and sometimes retreats from the conversation entirely 3 11 12 15 110.

Her playful manner also serves a social purpose. She uses teasing to soften the authority and brilliance associated with her presidency and make herself less unapproachable. With Yeyou, she particularly values being able to interact comfortably as an equal 93.

As president, she favors negotiation over simply suppressing dissent. She wants to resolve the Course 1–Course 2 conflict without creating another form of unequal treatment, and is willing to consider arguments that challenge existing policy 45 46 49.

Her concern for Yeyou reveals a more forceful side. She respects his privacy, discourages others from probing his secrets, and offers help without demanding disclosure. Privately, however, she can issue cold, uncompromising instructions to her aide and dismiss objections involving her father when arranging Yeyou’s protection 100 123 134.

Abilities & Skills

Acceleration, Compound, and Perception Magic

Mayumi identifies acceleration magic, compound magic, and perception magic as her stronger fields 62.

• Notices Yeyou’s unusual magic after he switches it off, surprising him because he considers its inactive state exceptionally difficult to detect 5.
• Yeyou suspects a secret Saegusa-family technique, but the encounter does not establish how she detected it 5.
• Senses a fluctuation of psions when Yeyou uses magic while observing Jumonji’s Phalanx 139.

Precision Shooting

Her shooting skill earns her the epithet “Fairy Sniper” 80.

• Accurately distinguishes and destroys her assigned targets even when red and white discs cross paths 80.
• With Yeyou’s enhanced CAD, destroys targets so quickly that observers judge the launching system unable to keep pace 80.
• Maintains accuracy despite the substantial increase in activation speed 80.

Crowd Ball

Mayumi uses a handgun-shaped CAD to return balls through magic rather than with a racket 83.

• Controls returns at angles her opponent cannot answer 83.
• Combines rapid reactions and enhanced tracking to win after a brief, one-sided exchange 83.
• Reports that the adjusted CAD runs stably without discomfort 83.

Magical Analysis

• Recognizes Phonon Maser when Shizuku Kitayama casts it and identifies it as an advanced spell 116.
• Explains the operating principles and short-range limitation of the countermagic identified as Cast Jamming 121.
• Understands that Jumonji cannot demonstrate Phalanx’s full power within a competition 139.

Leadership and Negotiation

• Recruits personnel for both Student Council work and competition support, including candidates whose ability others question 5 18 58.
• Mediates student confrontations and negotiates directly with Sayaka Mibu’s group 12 45.
• Handles the public Course 1–Course 2 discussion alone to avoid contradictions between multiple representatives 46.

Equipment / Weapons / Items

• Speed Shooting CAD — Personally calibrated by Yeyou; supports the speed and accuracy behind her decisive tournament performance 77 80.
• Crowd Ball CAD — A large handgun-shaped model enhanced for activation speed and dynamic tracking 83.
• Personal CADs — Mayumi asks Yeyou to calibrate her own equipment after experiencing his competition adjustments 80.

Yeyou states that the extraordinary enhancements are exclusive to his work and will not persist beyond the Nine Schools Competition; they are not established as permanent increases in Mayumi’s unaided ability 98.

Relationships

• Chiba Yeyou — Her junior, personal secretary, competition technician, and romantic interest. After Jumonji encourages her to pursue him, she becomes more openly affectionate and declares her intention to take the initiative. Yeyou describes them as “more than friends, but not quite lovers”; she trusts that their relationship will develop in time 5 55 66 98.
• Mari Watanabe — A close friend and fellow school leader. They tease one another about romance, cooperate on disciplinary matters, and share Yeyou as their competition technician. Mayumi worries about the risks of Mari using his experimental magic 10 12 62 75 76.
• Katsuto Jumonji — A friend and partner in organizing First High’s competition team. He encourages her to pursue Yeyou, considering both her feelings and the marriage expectations surrounding descendants of the Ten Master Clans 54 55.
• Miyuki Shiba — A junior whom Mayumi recruits as a Student Council secretary. Mayumi supports her competition efforts and recognizes her growing strength 18 90 112 113.
• Tatsuya Shiba — A junior whose capabilities she increasingly respects. She supports his Public Morals Committee appointment and recommends him as a competition technician despite doubts from others 18 19 58.
• Erika Chiba — A Course 2 student Mayumi helps recruit for the Public Morals Committee on Yeyou’s recommendation 17 18.
• Hanzou Gyoubushoujou Hattori — Her Student Council Vice President. She overrides his objection to Yeyou’s appointment and privately anticipates that his attitude toward Tatsuya and Erika will expose their abilities 4 5 19.
• Suzune Ichihara and Azusa Nakajo — Student Council colleagues who share her administrative workload and frequently tease her about Yeyou 6 17 22.
• Unnamed suited aide — Carries out Mayumi’s instructions to warn factions approaching Yeyou, monitor threats, and protect him. Mayumi sharply questions whether she has done enough to ensure his safety 123 134 135.

Notable Quotes

“However, I cannot solve this problem by creating new discriminatory treatment, because whether they are Course 1 Students or Course 2 Students, everyone is a student of First High School.” 49

“Please don't shoulder it all yourself.” 123

“You don't need to worry about my father. Just do your job, understood?” 123