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Manga / Kanojo ni Naru Hi

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Kanojo ni Naru Hi (The Day He Became A Girl) is a Manga series by Ogura Akane.

Miyoshi is always competing and losing against his childhood friend, Mamiya, who is good at everything and completely unable to resist a challenge. But their more-or-less friendly rivalry is broken when Mamiya is hospitalized and emerges as a girl. In Mihoshi and Mamiya's world, "emergence" is a natural process that maintains the ratio between the sexes. Whenever there aren't enough women some boys transform into girls. While emergence isn't exactly uncommon (tens to hundreds of cases every year) it usually happens in young children who are rapidly developing anyway, otherwise the resulting stresses on the body are very dangerous to teenagers and invariably fatal for adults.

Refusing to mope Mamiya, breezily returns to school unequivocally and seemingly unabashedly female, determined to seize life as a girl and equally determined to help Miyoshi overcome his severe gynophobia. But Miyoshi soon comes to suspect that there's actually a great deal of turmoil going on beneath Mamiya's seemingly happy-go-lucky surface.


In the sequel Kanojo ni Naru Hi Another Sagara, a short, slight, and girly-looking boy who has cultivated a tough-guy image to compensate emerges as a girl halfway through his second year of middle school and is forced to confront a stark choice between maintaining his identity as a boy and forging a new identity as a girl, a choice only complicated by a new attraction to Narumi, his rival for the affections of the cool, collected class representative Kurokawa.



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    Common tropes 
  • Author Appeal: All four protagonists go on to become medical professionals: Miyoshi becomes a biomedical researcher specializing in Emergence, Mamiya becomes a psychological counselor for Emerged youth, Sagara becomes a nurse and Narumi a medical doctor.
  • First Law of Gender-Bending: Emergence is implied to be always male to female. Reversions to male are possible with medical intervention but very rare, as it is implied to be a side effect of a "last step short of death" medical treatment.
  • Gender Bender: In this series, a small number of males rapidly become female, seemingly at complete random.
  • Teens Are Monsters: Inverted. The protagonist's classmates are, by and large, remarkably accepting and supportive with one or two exceptions. Even Shima is more of a tease than an antagonist. It's younger children and adults who tend to have and cause the most problems.

    Tropes found in Kanojo ni Naru Hi 
  • Allergic to Love: Mamiya has severe intimacy issues stemming from the breakup of her parent's marriage.
  • Aloof Big Brother: Subverted. Mamiya's love for her little half-sister Miki was alwasy unequivocal and freely given even before she changed into a girl.
  • Always Second Best: Miyoshi is constantly challenging and losing to Mamiya, be it soccer, Aikido, or academics...until she emerges. She still beats him in academics
  • Best Her to Bed Her: Played with and gender-flipped: Mamiya is so competitive she likes to keep Miyoshi "on the back foot" in order to maintain control of their relationship while Miyoshi gets the victory he's always desired every time he flusters her, so their love quickly evolves into a gentle competition to see who can make the other blush the most.
  • Chekhov's Skill: Miyoshi's family runs a dojo and both Miyoshi and Mamiya earned black belts, though the payoff doesn't come until their Big Damn Heroes moment in the sequel.
  • Childhood Friend Romance: Victorious Mamiya, eventually.
  • Compensating for Something: Mamiya's drive to excel at everything turns out to have some very ugly roots.
  • Cool Big Sis: Miki Mamiya practically worships her big sister Nao.
  • Dogged Nice Guy: Miyoshi dogged enough that he's willing to wait five years for Mamiya to wake from her second emergence.
  • Freudian Excuse: Mamiya's deep psychological need to excel at everything—even femininity—comes from her sense of Parental Abandonment, which her emergence only complicates by making her resemble the mother who abandoned her.
  • "Gift of the Magi" Plot: Chapter 13.
  • If It's You, It's Okay: Mamiya takes advantage of this to help Miyoshi work through his gynephobia and later decides it's also the reason why Miyoshi is the only boy she's interested in. It also inspires her to extend her second emergence until she's sure she'll remain a girl for Miyoshi's sake and ironically she emerges just after he finally admits that he'd still love her if she turned back into a boy.
  • I Know You Know I Know: Miyoshi and Mamiya's perpetual rivalry began because Miyoshi wanted to distract Mamiya from the loss of his mother. It continued because Miyoshi also wanted to defeat Mamiya in something and never managed it. It gradually becomes apparent that they both knew what Miyoshi was up to all along and went along with it for their own reasons
  • Ill Girl: Mamiya's emergence stressed her body a lot more than she lets on, and her health is a lot more fragile than she would have people believe.
  • Last-Name Basis: Miyoshi and Mamiya don't use each other's given names, Kyousuke and Nao. In fact, they don't even start using each other's given names until Miyoshi proposes, after they'd been dating for years and already have a sexual relationship.
  • Metamorphosis: The method of transformation, including cocoons.
  • Missing Mom: Mamiya has severe abandonment issues because her mother abandoned Mamiya and her father only to turn right around and start a new family with another man.
  • The Only One Allowed to Defeat You: The basis of Miyoshi and Mamiya's relationship, which later morphs into a Gender-flipped Best Her to Bed Her when Mamiya decides to engage on the romantic front.
  • Second Law of Gender-Bending: Played with: Mamiya seems to throw herself into femininity the same way she's attacked every other challenge, but Miyoshi soon realizes she's masking deeper psychological issues.
    It isn't until years later while contemplating motherhood that Mamiya finally realizes emergence wouldn't have evolved in the first place if it weren't an effective reproduction strategy, which means some degree of acceptance is probably inevitable for most people. She expounds a bit further on this when counseling Sagara in the sequel (see below).
  • Shameless Fanservice Girl: Mamiya in her first bikini. Miyoshi figures she's overcompensating, which Mamiya finally admits years later on their honeymoon.
  • Star-Crossed Lovers: Mamiya and Miyoshi, especially since they keep unintentionally friendzoning each other.
  • Stepford Smiler: Mamiya keeps up a solid front and only breaks down when it becomes apparent she can no longer compete physically with Miyoshi.
  • Strong Family Resemblance: Post-emergence Mamiya looks remarkably like the Missing Mom who abandoned her, causing her much angst.
  • Third Law of Gender-Bending: Mamiya's so determined to tackle femininity head on she practically demands to be treated according to the third law during her reintroduction to the class. Miyoshi figures it's just another sign of her need to always master her emotions, though later chapters imply her close relationship with her baby sister may play into it as well, because the last thing she wants to do is give Miki the impression that there is something wrong with being a girl. Lampshaded when Mamiya admits to Miyoshi that she doesn't always understand "girly" thinking despite her outward behavior and appearance.
  • Transgender Fetishization:
    • Mamiya shows off a skimpy bikini in the Beach Episode, Justified in-story as an indication of Mamiya's desire to show that she's still the calm, cool, always-in-control person she was before despite her Gender Bender and hidden illness, something she only admits indirectly several chapters and many years later when she confesses to Miyoshi that she refused to change or bathe with the other girls during that trip.
    • Mamiya wears a Naked Apron in Chapter 14. Justified in-story as an attempt by the hypercompetitve Mamiya to fluster Miyoshi for a change so she can regain the upper hand in their relationship. Her ambivalence is lampshaded by the fact that she retains her underwear (though she makes sure Miyoshi can't see that.)

    Tropes found in Kanojo ni Naru Hi Another 
  • Abusive Parents: There's a reason Sagara lives with his uncle. It isn't pretty. His mother later tries to sell him into the sex trade or for medical experiments, it's not clear which and she doesn't particularly care. He claims (falsely, it turns out) that his parents are dead.
  • Accidental Truth: Narumi blurting out "I didn't expect you to be this cute" marks the first turning point in their relationship.
  • Adults Are Useless: subverted. All of Sagara's teachers and caseworkers are fully in the loop and appear genuinely interested in his welfare. They identify opportunities for him to re-identify as a girl but they respect his choices. For example they arrange for him to take the mandatory swim test on Sunday, so he won't be forced to reveal his secret to anyone who doesn't know it already.
  • Alternate Character Reading: Inverted, Aya and her deceased elder sister share the same name but it's written with different Kanji.
  • Armor-Piercing Question: "Can I see you as a girl?"
  • Aw, Look! They Really Do Love Each Other: Sagara's uncle Haruyuki initially seems aloof (Sagara certainly seems to think his uncle only took him in out of a sense of family obligation) but later events prove he genuinely cares and is actually paying close attention while not interfering. For example, he secretly bought Sagara a girl's uniform and a School Swimsuit just in case Sagara elected to re-identify mid-year, but never tried to force them on him.
  • Babies Ever After: The sequel reveals that Mamiya and Miyoshi eventually did get married and Mamiya, despite her fears, is happy as a young mother.
  • Because You Were Nice to Me: A recursive example: Sagara is grateful for Kurokawa's kindness even before he emerges, unaware that she's repaying him for the kindness he showed her in grade school.
  • Becoming the Mask: Kurokawa repeatedly demonstrates that she actually is the kind person she thinks she's only pretending to be.
  • Big Damn Heroes:
    • Nao and Kyousuke confronting the human traffickers after Sagara
    • Narumi going out of his way to take care of Sagara when he falls ill counts as well.
  • Bisexual Love Triangle: Sagara thought he and Narumi were straight-up rivals for Kurokawa's affections only to learn he's actually the apex of their love triangle thanks to the revelations prompted by his emergence. Narumi thinks he's jealous of Sagara's attentions to Kurokawa, when he's actually jealous of Kurokawa's attentions to Sagara. Unusually for a gender-bending triangle such as this, Sagara falling for Narumi makes him feel obligated to identify and present as female, but no one questions the social acceptability of dating Kurokawa as a girl—which Kurokawa herself pushes for Sagara to do, because she'd rather date someone who's completely female.
  • Class Representative: Kurokawa, though she is an atypical example.
  • Cool Big Sis: Nao and Miki are still extremely close and she spoils Miki unmercifully. Miki's friends even comment on Nao's "Big Sister Complex".
  • Conveniently an Orphan: Sagara's lack of parental guidance is certainly convenient for the author. It means he has no one at home influencing his gender choices.
    • Sagara's insistence that he is an orphan (even to himself) is psychologically convenient because it's less painful than the truth: his father is a deadbeat and his mother lost custody for abusing him.
  • Different for Girls: Sagara cites avoiding this trope as his primary reason for wanting to continue living as boy, But even though Sagara is hiding his Gender Bender he still has to deal with the physical changes, mainly (aside from the obvious) decreased strength and increased flexibility.
    • Subverted later when school lets out for summer vacation and freed from the requirement to play Sweet Polly Oliver Sagara discovers there are also positive aspects to Different For Girls, mainly clothing that's much cooler in hot weather and attracts positive attention from Narumi while deflecting negative attention from homophobes and bullies put off by his girly looks. Dressing
  • Distant Finale: Ten years on, Sagara and Narumi have gone on to become a nurse and a medical resident respectively. They're also busy planning their wedding while Kurokawa has finally broken with her parents over her refusal to get married.
  • Fantastic Racism: It turns out there can be a good deal of prejudice against the emerged, and they're prime targets for human traffickers.
  • Friendless Background: Subverted: Sagara tries to keep his classmates at a distance, but they mobilize to help him anyway.
  • The Gadfly: Shima needles Sagara and Kurokawa relentlessly until he discovers their secrets... then appears so taken aback by what he learns, especially from Kurokawa, that he doesn't do anything with the information.
    • Narumi needled Sagara into trying on girl's clothing in a classic example of reverse psychology—only to be unprepared for his own reaction to the results.
  • Gender-Bender Friendship: Inverted in that Sagara's Gender Bender allows him to make friends with a male.
  • Gender-Blender Name: Subverted in that the two explicitly gender bent characters have unambiguously gendered names: Aya (female) and Rinichi (male).
  • Hero of Another Story: Mamiya's little sister Miki is a classmate, and Narumi's lifelong friend. Mamiya herself is one of Sagara's Ministry of Health caseworkers.
  • Hide Your Lesbians: You'd think a society where some children spontaneously change sex would be more open minded about gender and sexuality, but Sagara has to choose between maintaining a male identity and pursuing a relationship with Narumi. It's not the sole motivation for his choice but it is the straw that breaks the camel's back. Sagara even hangs a lampshade on it, wishing he could walk hand in hand with Narumi and wondering why they can't.
  • It's All About Me: Sagara's mother's attitude in a nutshell. Not only does she blithely try to sell him to clear her debts, she actually expects him to go along with it for the sake of his dear old mom, and actually has the gall to ask him if her was going to abandon her when her plans fall through.
  • If It's You, It's OK: It's not clear if Kurokawa would be willing to accept a lover who is only physically female. Though she does appear willing to give it a try, she also tries to get Sagara to wear girl's clothing. The jury's still out on Narumi with respect to Sagara, but Sagara appears willing to apply this to Narumi.
  • Incompatible Orientation: After Sagara emerges Kurokawa reveals that neither he nor Narumi ever really had a chance wooing her because she's a lesbian.
  • I Want My Beloved to Be Happy: Kurokawa breaks up with Sagara when it becomes obvious (to her, he's still clueless) that Sagara is actually smitten with Narumi.
  • Knight Templar Big Brother: Nao. Played for laughs when she tells Narumi he isn't good enough for Miki only to switch instantly to isn't she good enough for you? when Narumi demurs. Turns up again in her Big Damn Heroes moment rescuing Sagara.
  • Jumping the Gender Barrier:
    • The ultimate reason Sagara eventually comes out to his classmates: he simply cannot abide hiding his affection for Narumi any longer or the rumors his affection raises about Narumi's sexual orientation.
    • Discussed when Nao counsels him that emergence's basis as a reproductive strategy means his sexual orientation is likely to swing towards men even as she acknowledges Kurokawa's lesbianism with "everyone is different."
  • Lady Looks Like a Dude: Sagara sucessfully hides his Gender Bender because he's always been small and has no figure to speak of.
  • Last-Name Basis: Sagara, Narumi, and Kurokawa are all on a family name basis, Sagara and Narumi because they are rivals and Kurokawa because that's typical of Japanese gender relations. Given names would imply a more intimate relationship than any of them are willing to admit.
  • Late-Arrival Spoiler: The two manga are published concurrently, meaning readers of the second title already know that Mamiya and Miyoshi's sometimes rocky relationship will have an eventual happy ending.
  • Meaningful Name: Sagara's given name is eventually revealed to be "Rinichi", which combines the kanji for "Cold" (or "Severe") and "One" (or "Primary"). While the "Blind Idiot" Translation ("Cold First") doesn't make a lot of sense in English the more idiomatic translation "Stoic First-born" pretty much describes him to a T.
  • The Mind Is The Plaything Of The Body: Subverted: gender identity and presentation appear subject to social pressures as much as biology. There is no indication that either Sagara or Kurokawa's sexuality was affected by their transformations and their choices of gender identity and presentation appear to be due more to timing and social circumstances. Kurokawa was viciously bullied by boys after she emerged in elementary school and promptly became a Replacement Goldfish for her beloved dead sister, whereas Sagara was already compensating for his girly appearance and has no one at home pressuring him one way or the other. Even so Sagara insists on remaining a boy primarily because he doesn't know how to live as a girl.
  • Mood Whiplash: Kurokawa's revelations in Chapter 11 represent a significant mood shift, even in a comic that is played more for drama than comedy.
    • The revelations about Sagara's parents in Chapter 14 certainly make the events of the earlier chapters much Harsher in Hindsight. No wonder the poor guy is afraid to get close to anyone.
  • Morton's Fork: Poor Sagara. A relationship with Narumi might force him to publicly re-identify as a girl, but a relationship with Kurokawa would also require him to be a girl even if she were willing to accept him pretending to be a boy in public. Either course requires surrendering his male identity. He even discusses this with Kurokawa, who recognises his dilemma.
  • The Nicknamer: Miki. Kurokawa is "Ayaya" and Sagara is "Rinrin". Ironically she doesn't use her nickname for her oldest friend Narumi ("Yu Yu"} all that often, though she is on a first name basis with him.
  • Oblivious to Love: Sagara either can't understand or is unwilling to admit why Narumi flusters him.
    • Narumi doesn't understand why he thinks of Sagara at random moments.
  • Old Friend, New Gender: Sagara is very surprised to discover that Kurokawa was a boy he knew back in elementary school.
  • One Head Taller: Narumi and Sagara, underscoring their OTP status
  • Parental Abandonment: Sagara insists his parents are dead; the truth isn't much prettier. Sagara's father is a ne'er do well gambler with a habit of running out on his debts, his mother is The Resenter, who hates him for being an ever-present reminder of his loser father... and for looking better than she does.
  • Poor Communication Kills: Sagara finally wears a girls' uniform (strictly for disguise purposes, he still isn't sure about re-identifying, but has to pretend long enough to take the swim test) then gets very upset when it appears not
to bother Narumi. Turns out Narumi is actually gobsmacked by Sagara's cuteness but fears admitting that would alienate Sagara. They do work it out eventually
  • Remember the New Guy?: Miki doesn't show up as a named character until Chapter 3, though she is depicted as an extra in Chapter One (She's the girl who accidentally squirts Sagara with the hose.)
  • Replacement Goldfish: Kurokawa is a voluntary replacement goldfish for her older sister (also named Aya), whom her parents prefered. She goes along with it because she loved her sister, is convinced that her sister was truly a better person, and feels tremendous guilt for jealously wishing her sister ill before she died.
  • Rescue Romance: Kurokawa is thrilled to discover that Sagara is now female because he saved her from bullies back in elementary school. Sagara feels a bit guilty because he didn't particularly want to rescue her, he just liked to fight.
  • Second Law of Gender-Bending: Sagara starts off accepting the physical change but unwilling to re-identify as a girl. Ultimately played straight, though in a more nuanced fashion than most examples: Sagara still misses being a boy sometimes but is ultimately thankful for her change because it kicked her out of a self-destructive rut and taught her important life lessons about love, friendship and caring for others. Rinichi Sagara was lonely, angry and bitter, Rin Sagara is loved and loves in return.
  • Secret-Keeper: Narumi and Kurokawa both agree to keep Sagara's secret, each for their own reasons. Shima learns Sagara and Kurokawa's secrets, but has kept quiet so far. Miki could easily learn everyone's secrets if she compared notes with her sister. Sagara believes Miki is a Secret Secret-Keeper because she is Nao's sister, though Miki herself has given no indication that she knows or cares about any of this,and Nao later assures Sagara that she's bound by professional ethics to keep his situation confidential.
  • She Is Not My Girlfriend: Narumi's instinctive denial to his Mother, while technically true and intended primarily to keep his mom out of his business, opens a huge emotional minefield for Sagara until Narumi points out that he's waiting for Sagara's permission to treat him as a girl.
  • Silk Hiding Steel: Kurokawa: Girly Girl on the outside, implacable as a glacier on the inside.
  • Stepford Smiler: Kurokawa hides a seething mass of grief, guilt and self-loathing under her cool, quiet and kind exterior and her secret joy that Sagara has emerged is just one more thing to feel guilty about. She even tells Shima "The real me is ugly" after he learns her secret.
  • The Stoic: Sagara, already isolated by his tough-guy image, goes to extra lengths to keep his secret and protect his beleaguered manhood
  • There Are No Therapists: subverted. The protagonist of Kanojo ni Naru Hi is the protagonist's caseworker in Kanojo ni Naru Hi Another and therapy is readily available
  • Third Law of Gender-Bending: Played with.
    • Kurokawa plays it straight: being a Replacement Goldfish for her older sister (and a Lipstick Lesbian uninterested in boys) she's a classic Girly Girl who tries to get Sagara into girly clothes using the pretext of exploring his options.
    • Initially subverted with Sagara, which actually causes more problems for him than playing it straight: the boys' uniforms don't fit right, cause him to overheat, and attract attention of the "it's hot, why are you still wearing your jacket?" variety that he'd prefer to avoid. Kurokawa's attempt to introduce him to feminine clothing caused his first major post-emergence freakout; His only concession on ilthe clothing front is a high-compression sports bra for comfort and concealment. However, he does reconsider this attitude when he notices the way his girls' uniform affects Narumi, even though he tells himself it's because skirts and dresses are cooler in hot weather. Even then the trope is not played completely straight because Sagara is more interested in attracting Narumi than looking girly.
    • Despite his insistence on presenting as a boy Sagara gets hit with other female stereotypes, in particular Men Are Strong, Women Are Pretty and Damsel in Distress.
    • Narumi actually subverts this trope (at least at first) because he's afraid openly expressing his attraction to Sagara in female clothing would alienate Sagara. It takes him a while to understand that Sagara actually wants to be considered attractive (or at least normal) to him, no matter how he is dressed.
  • Transgender Fetishization: A common problem In-Universe: Emerged children and teens are especially at risk for being kidnapped by human traffickers. Sagara's own mother tries to sell him to traffickers to clear her debts.
  • The Unfavorite: Kurokawa. Her parents tried to turn her into her deceased older sister after she emerged, even giving her the same name. She went along with it because she also believed her sister was a much better person and became a Stepford Smiler to hide her self-loathing.