Fukayama Natsuki

Biodata

Feature	Detail
Name	Fukayama Natsuki (深山菜月) 28 29
Family	Fukayama Midori (older brother); unnamed parents who work overseas 29 31 116
Age / Schooling	Third-year middle school student; expected to enter Izuki High School the following year 28 87 239
Height / Weight	156 cm; 89 lbs 29
Health Status	Normal 29
Academic Rating	S 29
Athletic Rating	A 29
Relationships	Akimoto Yoichi (adoptive older brother figure, study partner, and romantic interest); Suzuran Ayano (childhood friend and foster-sister-like figure); Suzuran Mari (maternal caretaker); Fukayama Midori (older brother); Kudo Miyu (relative and rival) 29 31 116 378 432
Personality	Timid and easily startled at first 28 29, highly curious, impatient, precocious, and sharp-minded 29 66 97, protective of those she cares about 41 96 116, prone to imagining the worst and filling gaps with her own assumptions 97, competitive and jealous in matters concerning Akimoto Yoichi 322 325 408 432, and increasingly affectionate and assertive around him 205 323 325
Interests	BL and doujinshi, tennis, super spicy food, studying, and cat-themed accessories 29 46 204 408
Favorite Colors	Green and brown 29
Living Situation	Frequently stays at the Suzuran household, where Suzuran Ayano and Suzuran Mari have cared for her during her parents' absence; later also spends time at the Fukayama family home while Akimoto Yoichi assists Kudo Miyu 96 116 378 380
Habits	Carries an anti-pervert alarm buzzer, studies with Akimoto Yoichi, and reacts strongly to his absence or attention toward other girls 96 97 168 411
Heroine Entry	“First Bird Inscription” — spending time with her increases both parties' learning ability by 20% and prevents memories from being forgotten 29
Key Events	Accidentally splashed curry on Akimoto Yoichi during their first meeting 29. Tried to expose his interactions with Suzuran Mari, but was blackmailed into silence 43 46. Moved into the Suzuran household to protect Ayano and Mari 96. Negotiated with Yoichi rather than attempting to expel him from the house 97. Helped address the threat of Suzuran Mari's parents' divorce 116. Became increasingly dependent on Yoichi's presence while studying 168. Defended Yoichi against Kudo Miyu and became involved in their rivalry 378 379. Competed with Miyu and other girls for Yoichi's attention 408 411 432.

Personality and Traits

Fukayama Natsuki is initially presented as a timid middle school girl who is frightened by Akimoto Yoichi's intimidating appearance, likened to a small animal encountering a predator 28 29. Beneath that first impression, however, she is exceptionally intelligent, observant, and precocious. Her sharp mind allows her to notice suspicious details in Yoichi's behavior that Suzuran Ayano and Fukayama Midori overlook, including deducing his contact with Suzuran Mari from the smell of curry on him 38 43 102.

Natsuki is fiercely protective of Suzuran Ayano and Suzuran Mari, who have effectively supported and cared for her while her own parents worked abroad. She is willing to confront Yoichi, bring an anti-pervert alarm to the Suzuran home, and even plead with her parents to intervene in the Suzuran family's marital crisis because of her concern for Ayano's happiness 46 96 116. Her protectiveness is also reflected in her disappointment with Midori, whom she sees as too oblivious and unreliable to help those around him 102 116.

Despite her intelligence, Natsuki is impatient and tends to construct elaborate conclusions from incomplete information. This tendency makes her wary of Yoichi and leads her to assume the worst regarding his intentions, though it also contributes to her determination not to be easily deceived 97 101. Over time, her hostility toward him softens into attachment. She becomes increasingly receptive to his praise, gifts, protection, and companionship, while still masking her feelings through bickering and threats to use her anti-pervert buzzer 136 137 194 205.

Natsuki is also highly competitive. Her rivalry with Ayano resurfaces after she sees a photograph of Ayano kissing Yoichi, and her rivalry with Kudo Miyu centers on both girls' attempts to monopolize Yoichi's attention 325 408 432. Although she claims to be happy for Ayano's progress with Yoichi, she privately fears losing the happiness she has found with him 432.

• Likes:

  • BL and doujinshi 29 46 204
  • Tennis 29
  • Super spicy food 29
  • Green and brown 29
  • Her older brother, Fukayama Midori, despite frequent frustration with him 29 116 240
  • Studying with Akimoto Yoichi, which makes her mind feel clear and focused 168
  • Gifts and praise from Akimoto Yoichi 136 137 194
  • Being protected and supported by Akimoto Yoichi 205 323 378
  • Cat-themed clothing and accessories 136 408
  • Teasing and bantering with Akimoto Yoichi 101 205 239

• Dislikes:

  • Akimoto Yoichi's teasing and his perceived villainous behavior, especially concerning her “ice cream” 38 102 205
  • Being falsely accused or manipulated 43 46 378
  • Fukayama Midori's naivety and inability to recognize others' intentions 102 116
  • Being unable to study effectively when Akimoto Yoichi is absent 168
  • Others taking her milk 168
  • Akimoto Yoichi becoming close to additional “little sisters” 239 411
  • Kudo Miyu's provocations and attempts to interfere with her relationship with Yoichi 378 379 408 432

Abilities and Heroine Buffs

Fukayama Natsuki has an S academic rating and an A athletic rating, giving her excellent potential in both intellectual and physical pursuits 29. She possesses extremely strong learning ability even before accounting for her heroine buff, and Akimoto Yoichi considers her young age and potential especially suited for intensive cultivation 29 38. Her intelligence is not limited to academics: she displays sharp observation, logical deduction, and a willingness to act independently when she believes Ayano or Mari requires protection 43 96 116.

Her presence substantially improves the efficiency of studying with Akimoto Yoichi. Natsuki herself finds it difficult to focus when he is absent, but becomes unusually clear-headed and productive when studying alongside him or in the familiar environment of his room 168. By Chapter 239, she is studying textbooks intended for Yoichi's grade, demonstrating the accelerated progress enabled by their time together 239.

Heroine Entry: First Bird Inscription

Fukayama Natsuki's heroine entry is “First Bird Inscription,” which states that “The first time is always impressive and unforgettable for a lifetime” 29. When spending time with her, both parties' learning ability increases by 20%, and nothing they learn is forgotten 29.

The effect is especially potent because Natsuki already possesses exceptional learning ability. Akimoto Yoichi believes that the buff may have helped Fukayama Midori enter Izuki Academy despite Midori's lazy lifestyle, and he intends to use it to catch up on middle-school science in approximately one year 31. He initially maintains contact with Midori partly because Natsuki's heroine buff is valuable to his academic ambitions 31.

The “First Bird Inscription” trait also carries an implication of strong attachment to formative first experiences. This contributes to the intensity of Natsuki's changing feelings toward Yoichi as their interactions become increasingly intimate and habitual 99 137 168.

Power Progression

Chapter	Advancement	Details
29	Heroine status revealed	Natsuki is identified as a heroine from the paid expansion, with S academics, A athletics, and the “First Bird Inscription” entry 29
31	Buff recognized by Yoichi	Yoichi identifies her learning buff as powerful enough to dramatically accelerate his science studies and possibly explain Midori's admission to Izuki Academy 31
118	Study partnership established	Natsuki regularly helps Yoichi study and falls asleep during a study session with him 118
168	Dependence on shared study environment	Natsuki struggles to focus without Yoichi but finds her mind clearer when studying in his room or alongside him 168
239	Advanced academic progress	Through their frequent study sessions and her buff, Natsuki begins studying textbooks for Yoichi's grade 239
341	Future student-council ambition	Natsuki expresses the ambition to become Izuki High School's Student Council President after entering the school 341

Relationships

Akimoto Yoichi

Akimoto Yoichi and Fukayama Natsuki's relationship begins with fear, suspicion, and a power imbalance before gradually becoming one of attachment, cooperation, and mutual protectiveness. Their first meeting occurs when Natsuki accidentally drops curry on Yoichi after being startled by his appearance. Yoichi responds calmly, while Suzuran Ayano reassures Natsuki that he is gentler than he looks 28 29.

Natsuki quickly becomes suspicious of Yoichi due to his interactions with Suzuran Mari and Ayano. She attempts to gather evidence against him by recording his admission that he met Mari, but Yoichi turns the situation against her and uses compromising information to force her cooperation 43 46. Natsuki initially submits to protect Mari and Ayano, seeing herself as the only person capable of recognizing the danger she believes Yoichi represents 46 102.

As Yoichi begins living at the Suzuran household, Natsuki's resistance shifts into reluctant negotiation. She realizes that expelling him would mean alienating herself from Ayano, who strongly supports him, and chooses to negotiate with him instead 97. Their daily interactions then develop through meals, studying, teasing, and Yoichi's increasingly open care for her 101 102 118.

Yoichi's gifts, protection, and acceptance of Natsuki's hobbies gradually weaken her hostility. After he defends her during an argument over BL manga, Natsuki willingly calls him “Yoichi Big Brother” and realizes she feels secure when he supports her 204 205. She becomes unable to study as effectively without him, reflecting the emotional and academic importance his presence has acquired in her life 168.

By the School Festival aftermath, Natsuki openly displays jealousy over Yoichi's closeness with Ayano and Mari. Though initially resistant, she accepts sitting on his lap in a crowded car and being fed a spicy snack, indicating her growing trust and affection 322 323. She later reveals a more docile side while alone with him and increasingly competes with other girls for his attention 325 408 411.

When Kudo Miyu attempts to manipulate Yoichi at the Fukayama home, Natsuki takes Yoichi's side despite Miyu's pressure. She sees Yoichi as an adoptive older brother who protects her in ways Midori does not, and she resolves to protect him in return 378 379. Her rivalry with Miyu continues as both seek Yoichi's attention and approval 408 432.

• Initial Encounter: Natsuki spills curry on Yoichi after being frightened by his delinquent appearance; he responds gently 28 29.
• Suspicion and Blackmail: Natsuki investigates Yoichi's contact with Suzuran Mari, but Yoichi uses her concern for Mari and Ayano to force her silence 43 46.
• Negotiated Coexistence: Natsuki accepts that she cannot simply remove Yoichi from the Suzuran household and negotiates with him instead 97.
• Study Partnership: Yoichi and Natsuki study together, with her heroine buff accelerating their learning 118 168 239.
• Growing Affection: Yoichi's gifts and protection lead Natsuki to soften and voluntarily call him “Yoichi Big Brother” 136 137 205.
• Jealousy and Competition: Natsuki becomes jealous of Yoichi's intimacy with Ayano and competes with Miyu and other girls for his attention 322 325 408 411 432.
• Mutual Protection: Natsuki defends Yoichi from Miyu's provocations and considers protecting him her responsibility at the Fukayama home 378 379.

Fukayama Midori

Fukayama Natsuki's relationship with her older brother Fukayama Midori is affectionate but deeply strained by his passivity, otaku lifestyle, and inability to perceive situations as she does. Natsuki originally tries to motivate Midori to protect his childhood relationship with Suzuran Ayano, warning him that Yoichi's growing closeness with Ayano is dangerous 30. However, Midori's distraction by Nagase Kumari and habitual indecision repeatedly leave Natsuki disappointed 30 57.

Natsuki sees Midori as incapable of understanding Yoichi's true intentions or helping Ayano during difficult circumstances. When Yoichi begins living at the Suzuran residence, Natsuki feels isolated because Midori fails to recognize her concerns or the changing dynamics around him 102. During the crisis involving Suzuran Mari's parents' divorce, she dismisses Midori's offer to help because she believes he would only make Ayano's situation worse 116.

Despite her harsh assessment, Natsuki still cares about Midori. She makes breakfast for him, worries about his isolated lifestyle, and suggests giving him leftover cake from the Suzuran household 28 240. Her frustration arises less from indifference than from the belief that he is wasting opportunities to support the people who care for him.

• Early Encouragement: Natsuki urges Midori to show initiative toward Ayano and resist Yoichi's growing influence 30.
• Frustration with His Passivity: Natsuki criticizes Midori for being unable to understand social situations or recognize Yoichi's influence 102 116.
• Care Despite Conflict: Natsuki prepares breakfast for Midori and remains concerned about his lonely, unhealthy lifestyle 28 240.
• Shift in Priorities: As she becomes closer to Yoichi, Natsuki increasingly regards Yoichi rather than Midori as the person she can depend on 205 378.

Suzuran Ayano

Fukayama Natsuki and Suzuran Ayano are childhood friends and neighbors with a sister-like relationship. Ayano has long been a major source of comfort and support for Natsuki, particularly while Natsuki's parents are overseas 29 31 116. When Natsuki accidentally spills curry on Yoichi, Ayano immediately comforts her and assures her that Yoichi is a good person 29.

Natsuki is highly protective of Ayano and initially moves into the Suzuran residence to guard both Ayano and Mari from Yoichi. She brings an anti-pervert alarm and intends to remain nearby for an extended period, believing that she alone understands the danger he poses 96 97. She also takes immediate action when she learns of the possible divorce involving Mari's parents, contacting her own mother out of concern for Ayano's emotional well-being 116.

Their relationship becomes increasingly complicated because both girls care deeply about Yoichi. Natsuki becomes jealous when she sees Ayano's closeness with him, especially after seeing their kiss commemorated in a School Festival photograph 322 325. While she wants Ayano to be happy, Natsuki privately fears that Ayano's initiative will reduce the time and affection Yoichi gives her 432.

• Childhood Friendship: Natsuki and Ayano have known each other since childhood and grew up as neighbors 29 31.
• Maternal Support: Ayano and Mari help care for Natsuki while her parents are abroad 116.
• Protectiveness: Natsuki moves into the Suzuran household to protect Ayano and Mari from Yoichi 96.
• Concern During Family Crisis: Natsuki tries to prevent the effects of Mari's parents' divorce from hurting Ayano 116.
• Romantic Rivalry: Natsuki's jealousy of Ayano intensifies after seeing Ayano and Yoichi's kiss 322 325 432.

Kudo Miyu

Kudo Miyu is a relative of Natsuki and one of her most direct rivals. Natsuki has unpleasant prior memories of Miyu and refuses to discuss her when Yoichi asks about prospective Izuki High School students from Natsuki's middle school 239. After Miyu enters the Fukayama household, their hostility becomes open and persistent.

Miyu repeatedly provokes Natsuki, uses Natsuki's room and belongings, and attempts to manipulate the household's sleeping arrangements to stay close to Yoichi 378 379 380 419. Natsuki is intelligent but comparatively guileless, leaving her vulnerable to Miyu's psychological manipulation 378. Even so, Natsuki refuses to abandon Yoichi and stands up for him when Miyu tries to use him for her own plans 378 379.

Their rivalry later expands into direct competition over Yoichi's attention. Natsuki wears cat ears, white stockings, and bells to counter Miyu's attempts to appear more mature and feminine before him, receiving a favorable reaction from Yoichi 408. In private, Miyu attempts to exploit Natsuki's guilt over Ayano and encourages her to prioritize retaining Yoichi's affection over Ayano's happiness 432.

• Prior Animosity: Natsuki has a strongly negative reaction to the mere mention of Miyu before Miyu's arrival 239.
• Household Conflict: Miyu provokes Natsuki, takes over her room, and seeks to control the household's arrangements 378 379 380.
• Manipulation and Defiance: Miyu manipulates Natsuki's emotions, but Natsuki remains defiant and protective of Yoichi 378.
• Competition for Yoichi: The two compete through clothing, accessories, and attempts to gain Yoichi's attention 408 432.

Key Events and Plot Points

• First Encounter with Akimoto Yoichi (Chapters 28–29): Natsuki is startled by Yoichi's delinquent appearance and accidentally spills curry on him. Yoichi remains calm, while Ayano comforts Natsuki and reassures her that he is kind. Yoichi subsequently discovers Natsuki's heroine status, exceptional academic and athletic ratings, and learning-related buff 28 29.

• Natsuki Encourages Midori to Protect Ayano (Chapter 30): Natsuki urges Midori not to give up on Ayano, warning him that Yoichi's growing closeness with her could be dangerous. Midori briefly resolves to act before becoming distracted by a message from Nagase Kumari 30.

• Discovery of the First Bird Inscription Buff (Chapter 31): Yoichi recognizes that Natsuki's heroine entry increases learning ability by 20% and ensures that knowledge is not forgotten. He decides to deepen his connection with her in order to accelerate his own education 31.

• Natsuki Accuses Yoichi of Corrupting Suzuran Mari (Chapter 43): Using the smell of curry as evidence, Natsuki deduces that Yoichi has encountered Mari and records his partial admission. Her attempt to expose him demonstrates her intelligence and her determination to protect the Suzuran family 43.

• Yoichi Forces Natsuki's Silence (Chapter 46): Yoichi blackmails Natsuki with compromising information connected to her mother and gains access to her phone, where he discovers her extensive doujinshi collection. Natsuki submits in order to protect Mari and Ayano, though she remains resentful and fearful 46.

• Natsuki Moves into the Suzuran Household (Chapter 96): Natsuki arrives at Ayano's home with belongings for a prolonged stay and an anti-pervert alarm. Her decision is motivated by her desire to protect Ayano and Mari while Yoichi stays there after losing his possessions in a fire 96.

• Natsuki Negotiates with Yoichi (Chapter 97): After observing Ayano's growing affection for Yoichi, Natsuki realizes that trying to expel him would only isolate her from the Suzuran family. She confronts him with her anti-pervert alarm and chooses negotiation over direct opposition 97.

• Growing Domestic Familiarity (Chapters 101–102): Natsuki becomes accustomed to Yoichi's presence in the Suzuran house, eats the breakfast and bento he prepares, and embarrassedly thanks him as “Yoichi Big Brother.” Nevertheless, she continues to believe she alone sees his true nature 101 102.

• Concern for Ayano During the Divorce Crisis (Chapter 116): Natsuki calls her mother and demands that she help prevent the divorce of Mari's parents, fearing its effect on Ayano. She rejects Midori's offer to help, believing he is incapable of offering Ayano meaningful support 116.

• Study Partnership and Emotional Dependence (Chapters 118, 168): Natsuki studies with Yoichi and falls asleep on his lap. Later, she finds herself unable to focus properly when he is away, while his room and presence restore her sense of concentration 118 168.

• Yoichi Defends Natsuki's BL Hobby (Chapters 204–205): While shopping for a gift, Natsuki argues with other customers over copies of a BL manga. Yoichi intervenes on her behalf, buys both copies, and later explains that he protected her simply because others had tried to mistreat her. Natsuki begins to view him as someone she can rely on 204 205.

• Jealousy After the School Festival (Chapters 322–323): Natsuki sulks after seeing photographs of Yoichi and Ayano kissing. During the ride home, Yoichi lets her sit on his lap due to the lack of space and feeds her a spicy snack, which she reluctantly accepts 322 323.

• Renewed Rivalry with Ayano (Chapter 325): After seeing Yoichi and Ayano's kissing photograph, Natsuki's competitive feelings toward Ayano return. She nevertheless shows a notably affectionate and compliant side while alone with Yoichi as they move gift boxes together 325.

• Conflict with Kudo Miyu at the Fukayama Home (Chapters 378–380): Miyu attempts to manipulate Natsuki and use her as leverage to keep Yoichi at the Fukayama household. Natsuki stays because she refuses to leave Yoichi alone with Miyu and regards protecting him as her responsibility 378 379 380.

• Cat-Themed Competition with Miyu (Chapter 408): Feeling threatened by Miyu's attempt to attract Yoichi through white stockings and cat accessories, Natsuki wears her own white stockings, bells, and cat ears. Yoichi reacts favorably, intensifying Miyu's jealousy 408.

• Rivalry Among Yoichi's Female Companions (Chapter 411): Natsuki argues with Miyu and Shiraishi Wakane over proximity to Yoichi at the Baseball Club. She also learns that Nagase Kumari has feelings for Yoichi, adding another perceived rival 411.

• Guilt and Selfishness Regarding Ayano (Chapter 432): While speaking with Miyu, Natsuki admits through her reactions that she wants Ayano to be happy but fears losing her own place beside Yoichi. Miyu exploits this conflict, urging her to prioritize their shared position in Yoichi's life 432.