Sakayanagi Arisu

Biodata

Feature	Details
Name	Sakayanagi Arisu (坂柳有栖)
Gender	Female
Affiliation	Class A, Advanced Nurturing Academy 2
Occupation/Role	Class A student; Class A Commander Tower during the Selection Project Exam 326 334
Status	Active
First Appearance	Chapter 2

Background / History

Arisu was born with congenital heart disease. Unable to engage in strenuous exercise, she spent much of her childhood indoors reading and playing chess; the isolation made her mature, intelligent, and lonely from an early age 348.

She entered the academy with a private obsession: to defeat Ayanokoji Kiyotaka, whom she understood to be the White Room's “highest masterpiece,” and prove that natural genius surpasses artificial cultivation 5. Her health initially required her to rely on a cane and excluded her from ordinary physical activities 142 210.

Appearance

Arisu is a petite, doll-like girl whose frail appearance sharply contrasts with her poise and calculating nature.

• Silver-white hair and pale, nearly translucent skin 2
• Violet eyes and a refined, delicate profile 2
• Slender build, with faint veins visible beneath her skin during periods of poor health 127
• Commonly carries a cane and wears a white beret 4 142
• Later begins walking without her cane following treatment and rehabilitation, though she sometimes continues to carry it out of long-standing habit 546 630
• Wore a white ski suit during the Hokkaido Educational Trip 665
• Bought and wore fluffy white gloves that Tetsu selected for her during the trip 679

Personality

Arisu presents herself with an elegant smile, calm speech, and an air of harmless fragility, but she is intensely competitive and openly contemptuous of mediocrity. On her first day in Class A, she dismissed self-introductions as childish and argued that trivial skills only expose weaknesses 2.

Highly analytical, she habitually treats people as variables, rivals, or pieces in a larger game. She quickly recognized Kazehara Tetsu’s support as an investment in Class A’s power structure rather than simple agreement 9. She is equally willing to exploit others’ assumptions, such as performing helplessness before Class D to secure their sympathy 142.

Despite her pride, Arisu accepts defeat without excuses. After losing the midterm wager to Tetsu, she formally acknowledged the loss and honored its condition 45. Her relationship with him gradually reveals a more playful, vulnerable, and affectionate side, though she continues to frame intimacy and loyalty in strategic terms 47 209 239.

Arisu can also be quietly possessive where Tetsu is concerned. Although she accepts his connections with other girls, she playfully expresses jealousy and takes a particular interest in girls who occupy a special place in his life, including Kushida Kikyo 463 655 660.

She is discerning about purchases and dismisses generic, impractical souvenirs. Despite initially considering the fluffy gloves Tetsu chose too childish for her image, she bought them after trying them on and hearing that he thought they suited her 678 679.

Abilities & Skills

Chess

Arisu is an exceptionally skilled and aggressive International Chess player.

• Opens games confidently and develops pieces with speed and solid technical foundation 11
• Favors sharp king-side attacks and actively creates tactical opportunities 11
• Uses chess as a way to assess opponents and deepen her understanding of them 9
• Lost her first documented match against Kazehara Tetsu after his precise defense and positional counterplay 11
• Declined the International Chess Club’s invitation because its members were beneath her standards 11
• Later acted as Class A’s true strategist in Tetsu’s International Chess match against Ayanokoji, issuing moves through the Commander Tower intervention authority 339
• Used the full thirty minutes of her intervention to directly test Ayanokoji’s ability, judging her resulting slight positional disadvantage as recoverable 340

Strategic Analysis and Manipulation

Arisu excels at reading motives, exploiting perceptions, and directing group strategy.

• Identified Tetsu’s attempt to gain her attention and secure a favorable place in Class A’s hierarchy 9
• Used her apparent physical weakness to manipulate Class D students into offering sympathy and goodwill 142
• Recruited Shiina Hiyori and Kushida Kikyo while helping form a four-class alliance 268
• Anticipated Ryuen Kakeru’s replacement of Class D’s Commander Tower before it was publicly revealed 332
• Evaluated Class C’s seven-a-side football strategy and immediately identified its reliance on Hirata Yosuke’s individual influence 334
• Helped oversee Class A’s cross-grade written-exam team arrangements, a responsibility Tetsu considered well within her capabilities 366
• Supported Tetsu’s plan to exploit the Free Ride Exam’s rules to secure a large increase in Class Points for Class A 399
• Approached Kushida during the Hokkaido Educational Trip while concealing her awareness of Kushida’s private connection to Tetsu 660

Class A Command

Arisu is trusted as one of Class A’s foremost intellectual leaders.

• Maintains her own faction within Class A, opposite Katsuragi Kouhei’s group 127 128
• Was unanimously selected as Class A’s Commander Tower because of her intellect and Protection Points 326
• Managed Class A’s available members across the Selection Project Exam’s events 334
• Reserved her intervention authority when Class A’s existing academic advantage made direct interference unnecessary 338
• Intentionally weakened Class A’s early long-rope lineup to preserve stronger members and expose Class C’s poor coordination 335
• Revealed to Horikita that Class A’s broader strategy was to exceed the usual participant limit and deploy its strongest students in multiple events 335
• Took Onodera Kayano aside after her transfer to Class A, beginning to incorporate the new student into Class A’s circle 563

Skiing

Following her recovery, Arisu began learning to ski during the Hokkaido Educational Trip.

• Initially had no skiing experience and intended to rely on Tetsu during the trip 660
• Sought Tetsu out as her personal instructor after completing a beginner lesson 665
• Rapidly improved her basic stance, braking, turning, and movement under his instruction 665
• Progressed from swaying while standing to gliding smoothly on level ground and practicing small turns; Tetsu caught her when she lost her balance during one turn 677
• Found skiing more enjoyable and interesting than she had expected 678

Health and Rehabilitation

Arisu’s congenital heart disease long limited her mobility, endurance, and exposure to heat or cold.

• Hot springs and cold outdoor conditions could quickly overstrain her body, causing dizziness, rapid breathing, and exhaustion 210 240
• She initially could not participate in physical education or Sports Festival events 142
• Kazehara gave her a potion that repaired her heart and significantly improved her congenital condition 345
• Following treatment, she began rehabilitation and entered the 100-meter sprint without her cane 544 546
• She completed the race in 18 seconds and finished last, but regarded participation itself as a step toward living normally 547 548
• She later described the congenital heart disease as fully cured, explaining that the cane remained primarily a habit developed during her years of illness 630
• During the Hokkaido trip, her fingers became cold and numb outdoors; warmth in a shop helped them recover 678

Relationships

• Kazehara Tetsu — Began as a rival and mutual observer. After losing their midterm wager, Arisu became his girlfriend; their relationship develops through strategic partnership, mutual trust, and open acceptance of an unconventional arrangement 29 45 213 239. Tetsu cured her heart condition, supported her rehabilitation, and later personally instructed her in skiing 345 665. Noticing her cold hands during the Hokkaido trip, he selected warm white gloves for her; she bought them despite her initial doubts about their appearance because he had chosen them and said they suited her 678 679.
• Sakayanagi Narimori — Her father and the academy chairman. He is deeply concerned for her happiness and health, and ultimately accepts her relationship with Tetsu 210 348. After being reinstated as chairman, he continued to meet with Arisu and Tetsu and offered support for their future plans 495 497.
• Ayanokoji Kiyotaka — Her long-sought White Room rival. Arisu entered the academy intending to defeat him and prove the superiority of natural genius 5. During the Selection Project Exam, she finally tested him indirectly by directing Tetsu’s moves during their International Chess match 339 340.
• Katsuragi Kouhei — Leader of the opposing Class A faction. Arisu initially wishes to remove him from the equation, reflecting their competing approaches to Class A leadership 127.
• Kamuro Masumi — A Class A associate who follows Arisu’s lead and assists with her safety during rehabilitation efforts 268 544.
• Horikita Suzune — Rival Commander Tower from Class C during the Selection Project Exam. Their exchanges expose Arisu’s unwavering confidence in Tetsu’s strength 333 334.
• Onodera Kayano — Assisted Arisu after her 100-meter sprint and learned that Arisu’s recovery was connected to Tetsu 547 548. Following Onodera’s decision to use her Class Transfer Ticket on Class A, Arisu invited her to speak privately 563.
• Kushida Kikyo — A member of the four-class alliance whom Arisu recruited alongside Shiina 268. Arisu later sought to become acquainted with Kushida during the Hokkaido Educational Trip, motivated in part by her knowledge of Kushida’s hidden relationship with Tetsu 660.
• Kagihara Misaki — Tetsu’s mother. Arisu met her alongside Kamuro, spoke openly about her former heart condition and its cure, and was recognized by Misaki as someone special to Tetsu 629 630.

Story Role / Major Arcs

Class A Rivalry

Arisu establishes herself as a major Class A power on the first day of school by publicly challenging Katsuragi’s collectivist approach 2. She then probes Tetsu’s understanding of the school’s point system, recognizing him as an unexpectedly valuable and dangerous rival 4.

Chess Challenge and Midterm Bet

She invites Tetsu to the club orientation and challenges him to chess as a means of evaluating him 9. Though she loses the match, she vows not to lose again 11 12. Her desire for an absolute academic victory leads to a midterm wager, which she loses after Tetsu uses Personal Points to exploit a rule she had treated as a pure intellectual contest 29 45.

Class A Partnership

Arisu and Tetsu increasingly cooperate in Class A’s internal politics, alliance-building, and special-exam planning. She acts as a strategic equal in private discussions while allowing Tetsu to take the central leadership position 127 268 333.

Commander Tower

Class A chooses Arisu as its Commander Tower for the Selection Project Exam due to her Protection Points and strategic ability 326. She directs Class A’s lineups and personally controls Tetsu’s moves during his International Chess confrontation with Ayanokoji 334 339. This intervention allows her to fulfill her long-held desire to assess Ayanokoji directly, even though she is left slightly behind when the authority expires 340.

Recovery and Sports Festival

After receiving treatment for her heart condition, Arisu begins pursuing physical independence. She leaves behind her cane, participates in the 100-meter sprint, and accepts the difficulty of rebuilding her strength after years of physical limitation 345 546 548.

Her participation also brings her into contact with Onodera Kayano, who later transfers to Class A after winning a Class Transfer Ticket. Arisu subsequently takes the initiative to speak with the new Class A student 547 563.

Hokkaido Educational Trip

During the Hokkaido Educational Trip, Arisu joins a mixed-class group with Tetsu, Ichinose, Horikita, Kushida, Kanzaki, Kaneda, and Yamashita 658 659. She seeks an opening to approach Kushida while privately aware of Kushida’s connection to Tetsu 660. Having never skied before, she requests private instruction from Tetsu and makes rapid progress in the sport’s fundamentals 660 665. She continues practicing until she can glide smoothly on level ground, and Tetsu steadies her when she nearly falls while turning 677.

After admitting that she enjoyed skiing more than expected, Arisu takes a break with Tetsu to explore the resort’s shopping street 678. There, he notices her cold hands and selects a pair of fluffy white gloves. She initially objects to their childish appearance but tries them on, buys them, and continues wearing them after he assures her they suit her 678 679. The pair eat hot food before rejoining their group at the resort entrance 679.

Notable Quotes

“We’re Class A, not an interest-based club for making friends, isn’t it?” 2

“Because he is stronger, I follow. Because he is stronger, I trust.” 333

Trivia

• Arisu enjoys psychology and management books, though she also reads popular fiction genres for information-gathering purposes 12 544.
• She considers mainstream club activities an inefficient use of finite time 9.
• Her white hair was the first feature Tetsu explicitly identified as attracting his interest 546.
• Although she no longer requires her cane after recovering from her heart disease, she sometimes carries it from habit 630.