Sakayanagi Arisu

Biodata

Feature	Value
Name	Sakayanagi Arisu (坂柳有栖)
Alias(es)	Little Princess Sakayanagi; Princess Arisu—nicknames used by Kitagawa Kai 2 158
Gender	Female 2
Affiliation	Advanced Nurturing High School; initially First-Year Class A, later Class B after her class’s demotion 2 161
Occupation/Role	Student; class leader and head of the Sakayanagi faction 33 108 207
Family	Daughter of school chairman Sakayanagi Narimori 94
Partner	Kitagawa Kai 94 207
Residence	Faculty Apartment, Room 520, after winning the room-allocation discussion 235 245
Health	Born with a fragile heart and physical limitations; substantially recovers through Kai’s Heart Repair Fluid, though her stamina remains limited 65 93 158 283
First Appearance	Collides with Kai at a hallway corner 2

Background / History

Early Life and First Meeting

Arisu’s congenital physical limitations shaped her belief that intelligence could compensate for—and surpass—physical strength. She built her identity around the conviction that “wisdom is power” 65.

Her first encounter with Kitagawa Kai occurs when they collide in a school hallway, leaving her on the floor beside her cane. Despite her refusal of an infirmary visit, Kai carries her to Class A without waiting for permission. Her classmates’ questions about whether they are dating leave her embarrassed and determined to remember the incident 2.

Chess Rivalry

Arisu challenges Kai after his victories over the Chess Club’s senior players, wagering all 88,000 of her points. She loses but recognizes him as an interesting opponent and promises to overturn his confidence in a rematch. Having emptied her account, she subsequently asks Kamuro Masumi to lend her points 8 9.

Her curiosity extends beyond chess: she asks her father to investigate Kai’s background. A later defeat raises her affection further and leaves her committed to a maid-outfit wager, which she eventually revisits after her health improves 10 40 92 246.

Class Leadership Struggle

Arisu initially cooperates with Katsuragi Kohei to purchase Class B’s information about the school’s hidden rules for one million points. Their competing approaches soon divide Class A: she insists that she is already its leader and rejects Katsuragi’s calls for cooperation 14 33.

Her criticism of group tutoring reduces attendance at Katsuragi’s midterm study sessions. After Class B surpasses Class A’s average score, she temporarily loses her leadership position 49 64.

During the Uninhabited Island Exam, her diminished faction consists of Kamuro, Yamamura Miki, and Hashimoto Masayoshi. Arisu intends to regain authority by making Katsuragi experience a decisive failure. Class A ultimately scores zero and incurs a monthly payment obligation to Ryuen Kakeru’s class; Katsuragi suspects her involvement, but the passages do not establish that she caused every leak 108 122.

By the following semester, her class has fallen to Class B, where she holds decision-making authority 161.

Heart Treatment and Physical Recovery

Chapter	Development
93	Emotional distress triggers a collapse. Kai administers Heart Repair Fluid; on waking, Arisu notices smoother breathing and the disappearance of much of her longstanding chest tightness.
94	A medical examination confirms fundamental improvement in heart function. Doctors anticipate reduced medication dependency and the possibility of light physical activity.
102 124	She begins aerobic exercise with Kai and continues roughly weekly treatment. During the cruise, she has already taken four doses before receiving another.
158	Her physical measurements approach those of a normal person, although she still tires quickly.
181	She completes a Sports Festival 100-meter sprint safely, finishing seventh in her heat.
214	She joins the morning-running group and jogs one lap, with Kai matching her pace.
277 283	Her exercise remains limited to manageable jogging and walking. During a later morning run, she stops after three laps rather than overexerting herself.

Kai offers continued treatment while asking her to become his girlfriend. By the next chapter, she kisses him and calls him “Boyfriend-kun.” She keeps the treatment’s specifics secret even from her father, acknowledging only that Kai is responsible for her improvement 93 94.

Relationship and Shared Residence

At dinner with her father, Arisu defends Kai’s sincerity despite his admission that he dates several girls and wants to marry them all. She also states that she intends to build her own career after graduation rather than devote all her time to him 158 159.

Arisu later supports Kai’s request for additional Faculty Apartment usage rights, expressing a desire to meet the girls he acknowledges and play chess with him daily. During the competition for Room 520’s remaining bedroom, she reveals that her persuasion secured her father’s permission for the arrangement. This contribution settles the contest in her favor 223 234 235 245.

Living with Kai does not immediately resolve her insecurity about their relationship. She eventually arranges an evening of Chinese chess, wears the maid outfit from their earlier wager, and directly expresses that her concern is Kai himself—not outsiders’ judgments or the number of women in his life 245 246.

Paper Shuffle and Winter Break

Arisu leads Class B’s challenge against Class A in the Paper Shuffle exam. Rather than writing most questions herself, she manipulates their layout and answer distribution to create doubt and irritation within the rules. Class B wins with an average of 690 against Class A’s 678, gaining 100 Class Points 238 286 325 331 332.

She immediately cautions her classmates against treating the narrow victory as proof of lasting superiority. During the subsequent winter trip, she reassures her protective father that she can handle Kai. The group’s highest travel-spending tier is publicly attributed to her grand-prize draw, although several travelers recognize signs that Kai arranged the generosity 332 337 339.

Appearance

• Build: Small and delicate, with a pale complexion 2 181.
• Hair: Silver-white, sometimes worn loose over her shoulders 39 246.
• Eyes: Described as blue, blue-violet, or violet/purple in different passages 8 64 124 181.
• Uniform: Wine-red school blazer over an immaculate white shirt 39.
• Personal clothing: Wears her usual hat with a cream-colored dress during a summer outing 154.
• Bearing: Maintains an elegant posture and smile, including during confrontations and embarrassing situations 8 124 161.

Personality

Arisu is proud of her intelligence and enjoys challenging capable opponents. She regards herself as a natural leader, dismisses advice she considers unnecessary, and initially undermines cooperation when it conflicts with her preferred methods 33 49 238.

Her composure often functions as a weapon. When Totsuka Yahiko proposes exploiting her relationship with Kai for exam information, she exposes his lack of a plan and questions whether he would accept the personal sacrifice he demands from others 287.

Romance reveals a more vulnerable side. Kai’s teasing repeatedly embarrasses her, while Ichinose Honami’s competence provokes both admiration and jealousy. Nevertheless, Arisu insists that opposing Kai in class competition does not diminish her love for him 124 235 246.

Her priorities gradually broaden beyond victory and control. She comes to recognize Kamuro as a genuine friend rather than merely a useful subordinate, and later accepts her physical limits while valuing her present happiness over hypothetical achievements 272 283.

Abilities & Skills

Chess and Board Games

• Plays chess at a level that impresses senior Chess Club members; the narration suggests she could have defeated the club without Kai’s intervention 8.
• Develops aggressive openings and searches for counterattacks, but repeatedly loses to Kai’s system-assisted mastery 8 40.
• Practices alone by playing both sides of a chessboard and also plays Chinese chess with Kai 242 246.
• Takes up Go after reading about a human defeating a powerful Go AI. Against Kai with his master-level skill deactivated, she wins their first game by half a point; subsequent games alternate between wins and losses 282 290.

Intelligence Gathering

• Identifies Yamamura Miki’s low presence as useful for observation and assigns her to monitor Katsuragi and Ryuen 80.
• Initially recruits Kamuro because she considers knowledge of Kamuro’s kleptomania a means of ensuring usefulness and discouraging betrayal 272.
• Uses her father’s connections to request an investigation into Kai 10.

Psychological Strategy and Leadership

• Exploits exam rules through disruptive formatting, suspicious answer patterns, and awkward question placement rather than relying solely on difficulty 325.
• Attempts to capitalize on Nagumo Miyabi’s fear of Kai winning the Student Council election by demanding 50,000 points per vote; the passage establishes the demand, not a completed sale 220.
• Warns Class B against overconfidence after its narrow Paper Shuffle victory 332.
• Keeps romantic closeness separate from information theft: she explicitly refuses to use her relationship with Kai to obtain his class’s Sports Festival roster 167.

Limits

• Even after substantial recovery, her endurance remains below that of her regular exercise companions 158 283.
• Physical labor and wilderness survival skills are not areas she routinely practices, although she claims she could learn them easily 117.
• Kai’s chess mastery remains beyond her demonstrated ability; their more balanced Go matches occur only after he disables that skill 8 40 290.

Equipment / Items

• Silver cane — Used for support from her first appearance; she continues carrying it after significant health improvement 2 223.
• Heart Repair Fluid — Kai-supplied medicine that repairs her fragile heart through repeated doses 93 124.
• Board-game sets — Uses chess, Chinese chess, and a nineteen-line Go board 242 246 290.
• Maid outfit — Purchased to honor her chess wager and worn again when she considers the agreement incompletely fulfilled 92 246.
• Athletic shoes — Buys more than a dozen pairs for over 200,000 points, personally paying for her indulgence while valuing the pair Kai selects 272.

Relationships

• Kitagawa Kai — Boyfriend, chess rival, and lifesaver. Their affection does not eliminate competition between their classes 94 207 235.
• Sakayanagi Narimori — Doting, protective father and school chairman. Arisu influences his decisions but refuses to disclose the specifics of her treatment 10 94 235 337.
• Kamuro Masumi — Assistant and companion whose relationship with Arisu develops from pragmatic recruitment into explicitly acknowledged friendship 92 272.
• Katsuragi Kohei — Rival leader and later collaborator. His emphasis on unity repeatedly clashes with her arrogance and methods 33 108 238.
• Yamamura Miki — Intelligence-gathering subordinate. Miki feels both useful and uneasy about Arisu’s assignments 80.
• Hashimoto Masayoshi — Member of her reduced island-exam faction. His offer to reveal Class A’s leader to Kai is explicitly presented as his own initiative 108 115.
• Ayanokoji Kiyotaka — Intended opponent. Knowing his White Room origins, Arisu initially wants to prove that a “true genius” surpasses an artificially cultivated one 65.
• Ichinose Honami — Romantic rival and fellow Room 520 resident. Arisu challenges her authority but increasingly recognizes her dependability 234 246.
• Ryuen Kakeru — Rival and occasional strategic contact. Their hostility is intensified by the island-exam debt, and Arisu maintains boundaries when he seeks help against Kai 161 167.
• Totsuka Yahiko — Katsuragi supporter whom Arisu rebukes for proposing that she exploit Kai without offering a workable plan 287.

Affection Levels

These values measure Arisu’s affection toward Kai in his system, not her intelligence or physical strength.

Recorded Level	Chapter	Context
10 — “Perpetrator”	2	Recorded after their hallway collision; subsequent increases and decreases fluctuate during the classroom incident.
40 — “Curiosity”	8	Increases by 10 after their first chess match.
45 — “Curiosity”	40	Increases by 5 after another defeat.
75	94	Increases by 10 following confirmation of her medical recovery; Kai receives Stamina +1 as the reward.
100	204	Listed in Kai’s later system panel.

• Detecting Arisu as a recruitable character supplies Kai with the Master-Level Chess Skill support pack; this is his system reward, not an ability granted to Arisu 2.

Notable Quotes

“Class A has never needed to choose a leader. I've always been one.” 33

“Sometimes, I even stand against Boyfriend-kun from Class B's perspective. But that does not mean I don't love him.” 235

“But I care about you. Can you understand that?” 246