Mayumi Saegusa

Biodata

Power Progression

Background / History

Mayumi is Koichi Saegusa’s daughter and the older sister of Kasumi and Izumi. Her family’s enemies make security a continuing concern: bodyguards secretly protect her during her journeys to and from school 13 24.

Baifeng Uesugi grew up moving between the Saegusa and Yotsuba households. Koichi proposed making him Mayumi’s guardian after Maya Yotsuba added him as a guardian for Miyuki Shiba. Mayumi consequently knew him from childhood as “Brother Bai Feng” 3 10.

Mayumi was gravely injured during the repeated attacks targeting Baifeng. After twenty-three attacks over a year, he concluded that remaining with either family endangered those around him and left with Koichi and Maya’s reluctant agreement. Mayumi was not told why he disappeared and spent the following years hoping for his return 4 35 43.

Appearance

• General appearance: Described as beautiful and elegant, with long eyelashes, a high-bridged nose, smooth skin, and a slender waist 5 86 88.
• Travel clothing: Wears a lace dress and white sun hat when departing for the Nine Schools Competition 33.
• Competition clothing: Wears a miniskirt with safety shorts during preparation for her ball-scoring event 43.
• Magical equipment: Carries a CAD on her wrist 4.

Personality

Mayumi combines a friendly public manner with a mischievous streak. She approaches Tatsuya to offer help before they have been introduced, welcomes the Shiba siblings to lunch, and smooths over an awkward discussion about student council eligibility. Her playfulness also extends to committing Tatsuya to duties before securing his consent 4 10 11 29.

She is perceptive and particularly attentive to Baifeng. She questions his simultaneous spellcasting, recognizes the significance of Double Casting, and later shows awareness of his relationships with the girls around him. She explicitly denies romantic interest in Tatsuya, explaining that his strength and mysteriousness attracted her attention 35 36 66.

Her confidence gives way to vulnerability around Baifeng’s disappearance. She remembers their separation as exactly three years and two months and asks him never to leave without warning again. She can also be possessive: while genuinely caring for his injuries, she privately celebrates arranging to have his bedside to herself 43 63.

Mayumi takes student safety seriously. She stops unauthorized magic, restrains panicked spellcasting during the bus emergency, and later gives students a frank assessment of their evacuation options during an attack on the city 8 34 95.

Abilities & Skills

Magical Marksmanship

Mayumi holds the title “Fairy Sniper.” Baifeng has witnessed her abilities and identifies defense, rather than offense, as her principal weakness 91.

• Competes in the women’s ball-scoring event and is shown scoring successfully 43.
• Requests Baifeng’s assistance with CAD calibration before competing 41.
• Receives Baifeng’s support during her event, though she later clarifies that he was assisting from the sidelines 49.

Magic Cancellation

Mayumi directly decomposes Honoka Mitsui’s forming magic while intervening in a confrontation between students 8.

• Stops the spell before it becomes an attack.
• Reminds those present that attacking someone with magic outside self-defense violates both the law and school rules.
• The passage does not identify this intervention as Tatsuya’s innate Decomposition ability 8.

Magical Theory

Mayumi possesses knowledge of specialized magical technology through her Ten Master Clans background 14.

• Explains that Innate Magic stores spells in a CAD-like device that activates when supplied with psions 14.
• Discusses the repeated overwriting and interference-strength problems that obstruct practical flight magic 28.
• Recognizes Shizuku Kitayama’s use of Phonon Maser 54.
• Warns that competitors cannot safely master flight magic merely by learning it at the last minute 68.

Leadership and Administration

Mayumi directs student council recruitment and helps organize First High’s Nine Schools Competition team 10 11 27.

• Appoints Miyuki as secretary and Tatsuya to the Public Morals Committee 11.
• Helps recruit Baifeng as a magic engineer and accepts his condition that Tatsuya serve as his assistant 27 29.
• Coordinates emergency responses and delegates crowd-calming to Azusa’s specialized magic 34 95.
• Has begun handling Saegusa family affairs as Koichi gradually steps back from some responsibilities 33.

Equipment / Items

• Wrist CAD — Worn when she first meets Tatsuya; she later seeks Baifeng’s help calibrating her competition CAD 4 41.
• Personal terminal — Used to coordinate the return of her younger sisters and communicate with Baifeng 24 25 47.
• Absolute Defense card — prepared gift — Bears the image of a white shield. Based on principles derived from Phalanx, it creates a barrier against magical and physical attacks. Maya’s tests demonstrate protection against gunfire, spells, and close-range strikes; Mayumi is its intended recipient, not the person conducting those tests 90 91.

Relationships

• Baifeng Uesugi — Childhood companion known as “Brother Bai Feng,” later her fiancé. Their reunion reveals the depth of her attachment, and she personally asks her father to confirm their marriage arrangements 10 35 43 83 85.
• Koichi Saegusa — Father. Arranges protection for his children and supports Mayumi’s engagement to Baifeng 13 24 83 85.
• Kasumi Saegusa and Izumi Saegusa — Younger sisters. Mayumi helps arrange their return after they sneak out to a shopping mall 24 25 26.
• Miyuki Shiba — Student council recruit and fellow childhood companion of Baifeng. They share concern for him but also compete for his attention; Mayumi later talks Miyuki down after she loses control over news of Mayumi’s relationship with him 10 35 63 90.
• Tatsuya Shiba — Junior and fellow acquaintance of Baifeng. Mayumi admires his abilities, appoints him to the Public Morals Committee, and involves him in competition engineering despite his reluctance 11 29 36.
• Mari Watanabe — Close school colleague who works with her on disciplinary appointments and competition preparations. Mayumi stays beside Mari after her competition injury 11 27 46.
• Azusa Nakajo — Student council colleague and successor. Mayumi encourages her to use her calming magic during the city attack and entrusts the students’ evacuation to her 28 95.
• Katsuto Jumonji — Fellow competition organizer. He promises to protect Baifeng’s identity and handles the match demanded by the Master Clans Conference 27 72 73.
• Maya Yotsuba — Baifeng’s partner and an ally in Mayumi’s engagement. Maya welcomes Mayumi into their shared domestic life; Mayumi comes to regard her as the household’s first wife 88 89.

Story Role / Major Arcs

Entrance Ceremony and Student Council Recruitment

Mayumi first meets Tatsuya outside the entrance ceremony and introduces herself as student council president. Their connection through Baifeng emerges afterward, prompting her to arrange a longer conversation with him and Miyuki 4 5 6.

At lunch, she invites Miyuki to join the council. The rule restricting council membership to Course 1 students prevents Tatsuya from joining, but Mari proposes the Public Morals Committee instead. Mayumi enthusiastically makes the appointment despite his objections 10 11.

Nine Schools Competition

Mayumi helps assemble First High’s team, focusing on its shortage of magic engineering technicians. Tatsuya recommends Baifeng, who ultimately accepts on the condition that Tatsuya assist him 27 29.

The journey to the competition exposes Baifeng’s concealed identity. After questioning his Double Casting, Mayumi hears why he disappeared and embraces him in tears. She agrees to help protect his identity, and later obtains his promise never to leave quietly again 35 36 43.

During the tournament, Mayumi balances competing with staffing and safety decisions. She persuades Baifeng to enter surfing, adds him to Monolith Code, and later prevents him from competing again while injured. She also condemns the Master Clans Conference’s demand for a more spectacular match as childish interference 43 47 48 72.

Katsuto’s victory secures First High’s third consecutive championship after he agrees to preserve Baifeng’s secret 73.

Engagement and Return to School

Mayumi asks Koichi to confirm her marriage arrangements with Baifeng. Koichi subsequently states that the two are engaged and that she will deliver the marriage agreement herself 83 85.

She visits Baifeng at the Yotsuba residence, and their relationship becomes intimate. After a week together with him and Maya, she reluctantly returns to school to attend to graduation-related matters 86 88 89.

City Attack and Council Succession

During the attack on the city, Mayumi directs Azusa to calm the frightened students with her magic. Speaking as a former student council president and a representative of the Ten Master Clans, she explains the threats to the venue, shelter, and harbor without promising that any route is safe 95.

She affirms Azusa as First High’s new student council president and entrusts the students to her. Mayumi remains at the central control room with Katsuto and others when Tatsuya’s group arrives to destroy the thesis data 95.

Notable Quotes

“How could you do that? You disappeared for three years without a word. Don’t you know how much I missed you during those three years?” 35

“Bai Feng, I’ll remember what you said today. Don’t forget your promise.” 43

“A-chan, I’ll leave everyone to you.” 95