Characters / ONIMAI: I'm Now Your Sister!

The Oyama Family

Mahiro Oyama

Our Hero(ine?)

Voiced By: Marika Kouno

The protagonist of our story. After two years as a "Home Security Officer" (read: NEET), he wakes up one day to find himself transformed into a middle school girl.

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• Adaptational Nice Guy: The anime downplays or omits some of Mahiro's more questionable moments in the early manga chapters, such as the presence of very non-con books in his Porn Stash, or him sniffing Momiji's clothes and offering to rub her breasts "to help them grow" when he panics about becoming too much like a girl during Halloween.
• Adaptation Dye-Job: Downplayed; Mahiro's hair is completely silver in the manga, but it's silver with pink highlights in the anime.
• Aloof Older Brother: He grew distant from Mihari after her overachieving made him feel inadequate (which, in turn, made her try even harder for his attention). Thankfully, their relationship slowly starts to heal after Mahiro becomes her younger sister.
• Ambiguous Gender Identity: He starts out as a guy, but becomes increasingly more comfortable with living as a girl as time passes. However, he still insists he's a boy, uses the masculine pronoun "ore" for himself even after his transformation, and occasionally tries to "reclaim his manhood".
• Amnesiacs are Innocent: After Mahiro temporarily loses his memories from accidentally dropping a heavy box on his head, he becomes timid, easily frightened, and is even outright scared of the non-con adult manga in his room. Justified, as Mahiro regressed to that of an actual middle school girl and doesn't recognize his own room, leading him to believe he's been kidnapped by an evil pervert planning to make him a sex slave.
• Animal Motifs: He's sometimes given a visual comparison to elephants, or rather one particular part of his former male biology is. One time when he gives that comparison to his friends, they internally compare him to a sloth instead.
• Because You Were Nice to Me: This is pretty much the basis for his friendships with Kaede, Momiji, Asahi, Miyo, and Nayuta, as after years of judgment and belittling for not being as successful as Mihari, them being a group of endlessly kind individuals that are considerate of his wants and needs leaves Mahiro very appreciative to have people in his life besides Mihari that actually care for him as a person rather than his (lack of) accomplishments.
• Big Brother Instinct:
  • When Mihari gets genuinely sick for the first time in years, he opts to take care of the cleaning and cooking so his younger sister can rest and even goes outside his comfort zone to do so.
  • When Mihari tells him she has a date leading up to Christmas, he resorts to stalking her to find out who the man is so he can judge for himself if he's worthy of his sister's affections. When it turns out Mihari is just going out with her friend Kaede, he becomes extremely relieved.
  • While it turns out to be from a misunderstanding that gets corrected later on, when he first hears from Asahi that she's okay with being naked publicly because her older brother sees her naked, Mahiro assumes this means he's a pervert spying on his younger sister in the bath, and during his first meeting with Yuuya, he gives the innocent boy a pretty intense and uncomfortable silent treatment that has him leaving the house quickly.
• Brother–Sister Incest: Defied. While Mahiro is a perverted guy who likes manga and video games with very raunchy themes, he is not at all attracted to his sister, romantically or sexually, with him admitting he would never look at his sister like that. He even gets disgusted during moments where Mihari is trying to be sexy.
• Butt-Monkey: Being turned into a girl against his will was just the start of it, as he’s forced to take up many new female specific lifestyle changes, discovers through monthly bleeding and sometimes pissing himself in public that he is a fully anatomically correct female, is forced to go back to school as part of a cover story, is regularly emasculated by literal middle school girls, gets directly and indirectly insulted both for his lazy habits and being an irresponsible older brother, and Mihari harshly judges and berates him over his more perverted behavior, and these are only some of the broad overviews of what he gets put through.
• Childish Older Sibling: He's this to his more social, smart sister Mihari considering he hasn't left his house in two years and left the house chores to his sister, he has a lot of maturity and social skills to work on.
• Chivalrous Pervert: He's very much interested in hardcore non-consensual manga and eroge porn; with an outright stated implication his fictional fantasies extend to teenage girls. Yet he's always either aloof, embarrassed, or intimidated around real-life naked girls or potential sexual situations involving them. He also has some pretty clear reservations about acting on his more degenerate feelings when he has them towards real girls since the girls in question are often his classmates or close friends and he has zero attraction towards his sister.
• Comically Missing the Point:
  • When Mihari calls him out for showing an interest towards Momiji, Mahiro concedes her point that he really shouldn’t be thinking that way towards a teenager, but immediately gets distracted by the side-detail of whether him being with Momiji counts as yuri.
  • After hearing Miyo's warnings about how the cold makes specific exposed parts of you fatter to protect your body, he leaves his bedroom window open during winter in an attempt to make his breasts grow. All this does is leave a sick and miserable Mahiro in need of being rescued by Mihari.
• Easy Amnesia: Early on in the manga, a now much shorter Mahiro attempts to pull down a box off his shelf and accidentally drops it on his head, regressing his memories to that of an actual middle school girl. He's fine after a night of rest.
• Extreme Doormat: On top of only putting up a brief resistance to being turned into a girl against his will, he's generally prone to just letting himself get dragged into whatever activity Mihari or his friends want him to join them for. He gets a little better at asserting his desires more later on, but still generally just goes with the flow of what others want to do.
• First Law of Gender Bending: The transformation starts to wear off at several points in the manga. Each time, Mahiro chooses to take the drug again.
• First Period Panic: When he gets his first period as a young girl, he naturally freaks out when he goes to the bathroom and sees the blood. Justified, as Mahiro is formerly a male shut-in that was clearly never taught about periods. It also leads to Mahiro empathizing with and appreciating Mihari a lot more as he realizes his younger sister had to put up with his antics while dealing with her own periods for years by herself and never once complained about them to Mahiro.
• Foolish Sibling, Responsible Sibling: He's the foolish sibling to his responsible sibling Mihari.
• Fountain of Youth: Not only is he subjected to a Gender Bender, but his female body is around the age of a middle school girl. He eventually starts attending middle school due to Compulsory School Age, and his immaturity makes him struggle with that level of schoolwork even though he's mentally supposed to be in his twenties.
• Freudian Excuse: Being the older brother to a Child Prodigy and Teen Genius younger sister that was always praised by everyone while he was belittled and shamed for not measuring up to the insane standard she accidentally set up for him has left Mahiro with a desire to simply not bother with being social or successful.
• Gag Penis: Implied in the manga as a drawing of an elephant is used as a visual representation to the audience whenever Mahiro's comrade returns to him.
• Gender Vocabulary Slip: He normally uses "ore" in private and "watashi" in public, but slips on several occasions early on when startled or flustered.
• Genre Savvy: Mahiro correctly guesses his friends ignoring him around his birthday means they are planning a surprise party for him because of all the manga he's read with this exact premise.
• Girly Girl with a Tomboy Streak: Develops into this over time, at least from the perspective of those who don't know his secret. Mahiro learns to enjoy spa treatments, girl talk and wearing feminine clothes, but still enjoys playing video games and spending time with his male classmates Yuuta and Minato.
• Hikikomori: Has been one for over two years at the start of the manga. Mihari has to literally drag him out of the house, just for a jog.
• Hates Being Alone: Mahiro's increased awareness over just how unsatisfying his previous life-style was causes him to develop a mentality of not wanting to excessively spend all of his time by himself. He does still have strong desires to spend his days doing single person activities at home by himself, he just doesn't like going entire days without some form of interaction from another living person anymore.
• Hypocritical Humor: He internally bemoans Kaede only knowing mobile games when he first meets her, despite the fact that he's a mobile gacha game addict that plays them to an even more obsessive degree just to win seasonal outfits.
• I Call Him "Mister Happy": He uses the term "comrade" to refer to his penis.
• I Just Want to Have Friends: Despite his initial protests and general shut-in nature implying otherwise, Mahiro comes to realize the first time he's left home alone since becoming a girl that he wasn't truly satisfied with his former shut-in lifestyle and that he desperately wants companionship more than anything.
• Jerkass Has a Point: Mahiro's initial defensive attitude towards Mihari's remarks and dismissiveness of her desires at the stories start is at least understandable considering she had just forced him to become a physically underage girl without his consent and then started demanding he make a bunch of lifestyle changes immediately after she admitted to turning him into a teenage girl because she always wanted a younger sister to raise.
• Jerkass Realization:
  • Mahiro has something akin to this reaction after he has his first period as a biological girl as he realizes that Mihari has been dealing with her own periods for years while he was rather selfishly leaving her to handle this and everything else around the house by herself.
  • He assumed his fellow classmate Miyako was prostituting herself out for money based on her unintentionally suggestive language when mentioning how much "Daddy" spoils her. When Mahiro finds out he's her actual single father and Miyako has taken up the household duties to ease the burden of his workload, he's immediately moved to apologizing to her the next day.
  • When Asahi finally clarifies in confusion that her brother doesn't peep on her in the bath. It leaves Mahiro comically distraught over how rude he was to Yuuya during their first meeting for no reason.
• Lazy Bum: Before his transformation he was content to leave Mihari to handle all of the house chores and expenses by herself while he spent his days playing video games, reading adult manga, and watching anime. Even after his transformation into a young girl it still takes a long time and Mihari constantly coaxing him into healthier habits for him to start dropping the worst aspects of this part of himself. During stressful situations or long breaks away from responsibilities like school, he has a tendency to relapse into these old behaviors, albeit not to as extreme of an extent.
• Loser Protagonist:
  • Before the story even started, Mahiro was a jobless shut-in for two years who had no meaningful accomplishments to speak of. Then he got turned into a girl against his will and is forced to take up a bunch of new lifestyle decisions by his younger sister. He slowly starts to drag himself out of being one with the help of his sister and later the friends he makes along the journey to becoming more social again.
  • In a more comedic sense, he's regularly beaten and emasculated by actual middle school girls over things he really should be better at that don't require the strength of an adult male, like video games as he plays them all the time. Even that turns out to be a good thing though, as the experiences humble Mahiro's ego and shows his increasing willingness to interact with other people of his own volition regardless of whether or not it's only fun for him.
• Manchild: Before his transformation, he'd spent at least two years living off Mihari, causing him to regress as time went on. By the time the series starts, he's even more childish than the average middle-schooler.
• Man, I Feel Like a Woman: Attempts this shortly after his transformation, but Mihari puts a stop to it, convincing him the experience would literally blow his mind.
• Masturbation Means Sexual Frustration: Having been a nerdy shut-in with a sizeable Porn Stash, Mahiro references his old chronic masturbation habits as a male multiple times throughout the story. The very first thing he tries to do after being turned into a girl is to attempt testing out the new equipment and is only stopped by Mihari lying that female orgasms are one-hundred times stronger than a mans and he would likely die if he tried it. Which isn't even getting into how he always tries (and fails) to pleasure his "comrade" every time it comes back.
• Meaningful Name: Although it's spelled differently, "oyama" can refer to male actors performing female roles in Kabuki theater, fitting Mahiro's position of a man appearing as a girl.
• Men Can't Keep House: He ruined an entire load of his sister's laundry and he couldn't even make rice porridge without calling Kaede for advice. Justified, as it's the first time in years, quite possibly his entire life, that Mahiro has had to cook and clean while his sister is sick.
• Mirthless Laughter: He softly chuckles in relief when Asahi admits to him that Momiji told her and Miyo that she thinks he’s a good for nothing slacker because it means he doesn’t have to pretend to be someone he’s not.
• Mistaken for Pedophile:
  • Mahiro in general has a (rather understandable) fear he’ll get mislabeled by his friends as some perverted weirdo and have the police arrest and charge him as a sexual predator if anyone other than Mihari were to ever learn that he’s actually an adult man in a teenage girl's body. He even has a mini-freakout when he thinks Nayuta admitting she already knows he’s a man is her way of saying she’s going to report him to the authorities.
  • Mihari warns him in “Mahiro and the Selfie Boom” to not take lewd pictures of himself since it will be a crime when he turns back into an adult. He takes a single lewd picture of himself anyway, to which Mihari later finds out about due to Mahiro forgetting he took it.
  • When he is caught hiding in the attic during his mother's visit, he imagines how it must look to an outsider. His conclusion is, "Mahiro (the adult man) has kidnapped and locked up a young girl and brainwashed Mihari into a willing accomplice".
• My Sister Is Off-Limits: He doesn't say it directly, but he shows himself to be the type of guy that doesn't like the idea of his younger sister dating, more specifically dating a guy he's never met before, as he secretly follows her outside to one of the most public areas of the Christmas season entirely of his own volition just to find out who the guy is. He still continues to stalk Mihari even after finding out the "date" is just Kaede, partly at Momiji's suggestion that they might secretly be a lesbian couple out to do less than wholesome activities.
• NEET: Mahiro starts the series as a college dropout with no job, though he insists on calling himself a "Home Security Officer". He eventually starts attending middle school due to how much younger his transformation makes him look.
• "No. Just… No" Reaction: He tends to react with mocking indifference whenever Mihari ends up in a situation where she can be viewed as sexy or tries to be. When Mihari used the temporary gender bender potion to increase her breast size, he was outright disgusted from accidentally seeing the result.
• "Not So Different" Remark: Mahiro has an internal dialogue with himself about how Yuuya is as much of a pervert as most boys his age while rifling through his Porn Stash.
• Once an Episode: A large number of chapters/episodes start with him lazing about and/or excessively vocalizing a desire to just stay home right before he inevitably gets dragged out of the house to do some activity that often touches upon one of his weaknesses.
• Potty Failure: Because he is formerly an adult male that never learned about female biology or social customs involving female public restrooms, Mahiro ends up wetting himself a few times. Even months after the transformation he still wets himself on occasion due to a combination of embarrassment, stubbornness, and overestimating how much he understands what his new body can handle.
• Pretending to Be One's Own Relative: It doesn't come up often because most characters didn't know him before, but Mahiro's cover story is that he's his old self's youngest sister.
• Running Gag: Mahiro's frequent attempts at masculine bravado always end with making him look decidedly unmasculine even next to the efforts of actual middle school girls.
• Second Law Of Genderbending: Despite some early embarrassment, Mihari's efforts result in him being much happier in his new body.
• Secret-Keeper: He discovers only a day later that the female cosplayer he took pictures of at a doujinshi convention was his strict and no-nonsense homeroom teacher, Mari. When he asks her if she knows about "Love Master," Mari asks him to not tell anyone. Mahiro doesn’t mention a word of it to anyone else.
• Sweet on Polly Oliver: Happens during his first meeting with Momiji due to her tomboyish appearance. Mahiro mistakes her for a boy, feels attracted to her anyway, and gets flustered and scared thinking his new body is changing his preferences.
• Too Dumb to Live: He tried making his breasts grow by opening his windows overnight during winter on Miyo's warning that his body will send extra fat reserves to his exposed body parts to keep them warmer. He only doesn't die because Mihari finds him in a freezing cold induced daze in time.
• Unlimited Wardrobe: His wardrobe is extremely varied, with nearly every chapter and anime segment featuring a new outfit unless he spends it entirely in school uniform or other special clothes. This is presumably due to Mihari picking his clothes for him.
• Yank the Dog's Chain: In chapter 50, it seems like he'll finally be able to masturbate using his comrade. However, Mahiro instinctively takes the gender bender potion in a panic, which turns out to make it impossible for him to get an erection within the limited time he still has it. The chapter ends with him crying in bed while Mihari comforts him.

Mihari Oyama

The Younger Sister

Voiced By: Kaori Ishihara

Mahiro's younger (now older) sister, and the one responsible for his transformation. Wanting to impress her big brother, she pushed herself to overachieve, leading her to skip high school and move straight to college, where she developed her Big Brother Rehabilitation Project.

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• Adaptation Dye-Job: Downplayed; she has plain black hair in the manga, but the anime gives her some purple highlights as well.
• Accidental Pervert:
  • She's unintentionally grabbed Mahiro's comrade on two separate occasions.
  • She aggressively put both Kaede and Miyo through a make-out session while drunk.
• A-Cup Angst: While she normally doesn't suffer from this as her breasts are fairly modestly sized, after the beach trip where she gets outsized by Miyo and sees everyone paying attention to her even larger breasted friend Kaede, she starts to feel jealous of the attention they receive for their more impressive assets.
• Alcohol-Induced Idiocy: She loudly calls Mahiro "onii-chan" in front of everyone and later has intense make-out sessions with Kaede and Miyo while plastered drunk from drinking amazake.
• The Atoner: Some of Mihari's comments on the matter indicate she came to realize that her efforts to succeed to get Mahiro's praise and attention is what eventually led to the judgment and scorn he received from others for not being as successful as her and that her Big Brother Rehabilitation Project is her attempt to repair the unintentional damage she feels responsible for.
• Berserk Button: Mihari is usually patient with Mahiro’s antics, but Mahiro stating his intentions to or actually doing perverted things with his younger female body always brings out her most harsh and judgmental treatment of him.
• Blatant Lies: She tells Mahiro that female orgasms are one-hundred times more powerful than males and that he would likely die if he tried it before allowing his body to adjust to being a woman in an attempt to stop his chronic masturbation habits. Mahiro is so uneducated on female biology he didn't even have a concept for what a period was until he had one as a girl, so he naturally falls for his sisters obviously ludicrous lie.
• Breast Expansion: She drinks one of the temporary gender bender potions after seeing all they do for girls is give them large breasts too… well, give herself larger breasts.
• Brutal Honesty: As much as she loves her brother, Mihari doesn't mix words with him either.
  Mahiro: Who do you think I am anyway?
  Mihari: An unemployed good-for-nothing shut-in.
• Butt-Monkey: She receives smart remarks for wearing the same outfit all of the time, is either begrudgingly convinced or forced to dress up more femininely on a few occasions, gets outboobied by a middle schooler, and has Mahiro either mock her or be disgusted over her efforts to be sexier.
• Clingy Jealous Girl: Mihari is supportive of Mahiro having female friends, but she tends to get annoyed when Mahiro gives his friends more attention over her. Mahiro occasionally playfully mocks her for being a jealous attention seeker towards him.
• Desperately Craves Affection: Most of what she did in her life was that she's always wanted Mahiro's praise that lead her to work harder for more praise. Most things given to her by Mahiro are still kept like the hairclip that she always wears and a toy he won her years ago.
• Everyone Has Standards: She briefly considered taking advantage of her brother's amnesia to invoke a Raise Him Right This Time scenario. Mihari drops the idea almost immediately and opts to take her brother to the hospital for his head injury instead.
• Fear of Thunder: She was afraid of thunderstorms as a child, and keeps some of that fear in the present day, justifying it as being hit by lightning is extremely dangerous.
• Foolish Sibling, Responsible Sibling: The Responsible to Mahiro's Foolish. Mihari is the more mature and levelheaded of the two, while Mahiro spent much of his teen years relying on her.
• Grade Skipper: She's a teenager, but she was smart enough to skip high school entirely and attends college.
• Labcoat of Science and Medicine: She frequently wears a labcoat, highlighting how she's a Teen Genius who's skilled in scientific areas.
• Meaningful Name: "Mihari" (見張り) can mean "to stand watch" or "to guard", fitting her position as Mahiro's guardian.
• "No. Just… No" Reaction: Mihari is generally put off by Mahiro’s perverted antics and she shows her most aggressively judgmental behavior if she even suspects he's planning to do something lewd with his younger female body.
• Prone to Tears: She easily goes crying in happiness when Mahiro gives her unexpected signs of affection (such as Valentine's Day chocolate) and making her porridge when she was sick.
• Raise Him Right This Time: Early on in the manga when Mahiro temporarily loses his memories and regresses to an actual middle schooler, Mihari briefly entertains the idea of invoking this on her now amnesiac sister. She quickly drops the idea as she considers it taking things too far.
• Reed Richards Is Useless:
  • She has invented an instant sex-change potion, that also functions as a veritable age-reversing serum on top of that. The only thing she uses it for is to help her NEET brother come out of his shell, with the added bonus of indulging in her desire to have a little sister.
  • Later on, she discovers that all her instant sex-change potion does to girls is increase their breast size. The result is that she only uses it on herself, solely to make herself feel better out of jealousy over Miyo and Kaede having a bigger pair than her.
• Sheep in Sheep's Clothing: Mihari’s introduction gives off the impression she’s just a controlling and self-centered sister who's only superficially concerned about Mahiro’s well-being because it affects her directly. Proceeding chapters/episodes make it clear that Mihari genuinely loves and looks up to Mahiro and is actually very considerate of Mahiro’s feelings and limitations, even if she isn’t above literally dragging him out to do things he doesn’t want to in an effort to give him a happier and more satisfying life.
• Teen Genius: She's a teenager who's smart enough to attend college, and she even successfully makes a drug that turns her older brother into a middle school girl.
• Tough Love: Says some very unflattering things about her brother in the first episode, but only because she wants to break him out of his unhappy Hikikomori lifestyle.
• Wanted a Sister Instead: Mihari really does want to help her brother, but also always wanted to have a little sister. So, when she saw a chance to kill two birds with one stone, she jumped at it.
• Well-Intentioned Extremist: A mostly benign version. Changing your brother's body without consent is extremely ethically questionable, but she really does want to give him a happier life.

Matsuri Oyama

Mahiro and Mihari's mother, working abroad and unable to see her children.

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• The Ghost: For most of the story, she's never seen and only rarely mentioned.
• Mom Looks Like a Sister: She looks young enough that she really was mistaken for Mahiro's other sister at the first glance.
• Open-Minded Parent:
  • She knows about Mihari's experiment and approves of it.
  • She mistakes Momiji for Mahiro's boyfriend, and seems happy with her son dating a much younger boy.
• Parents as People: She can't be there for her children due to her work, but she still cares about them a lot, and sincerely apologizes for her absence when she gets an opportunity.
• Secret Secret-Keeper: She has known about Mihari's experiment since the beginning, and neither of them has told Mahiro about that.
• Shared Family Quirks: She shares some behaviors with her children, such as lazing around under a kotatsu like Mahiro, or playing dress-up with Mahiro and casually flipping his skirt to check his crotch like Mihari.
• So Proud of You: She is very grateful to Mihari for keeping the house all on her own and rehabilitating Mahiro.
• Strong Family Resemblance: She looks just like an older female Mahiro, minus the ahoge.
• Unseen No More: Come chapter 84, she comes home with a surprise holiday visit.
• When You Coming Home, Dad?: She works overseas with almost no time to visit her children. However, they still care about each other very much, and she makes frequent contact with Mihari offscreen.

Mahiro's Friend Group

Kaede Hozuki

The Gal

Voiced By: Hisako Kanemoto

Mihari's old schoolmate and all-around Nice Girl. She meets Mahiro early on in his rehabilitation, and quickly becomes a second sister to the boy-turned-girl.

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• Adaptational Curves: Her bust is decently sized in the manga, but she's absurdly stacked in the anime adaptation.
• Adaptation Dye-Job: She has red hair in the manga, while the anime makes it pink with blue highlights.
• Cool Big Sis: All of Mahiro's core friend group look up to her as an older friend and role model. She's even more of a sister figure to Mahiro than his biological sister!
• Feminine Women Can Cook: Her competence and eagerness to cook even in situations where she isn't obligated or expected to do so puts emphasis on her as the caring and responsible feminine type.
• Gyaru Girl: She's definitely a follower of the kogal subculture; she has dyed hair, is very fashion-conscious, frequently uses makeup and has a very bubbly personality.
• Informed Attribute: She’s supposed to come off as somewhat intimidating to Mahiro during their first meeting due to her being a fashion obsessed freewheeler, but the manga’s art style and her soft design doesn’t sell the image of Kaede being notably off-putting appearance or mannerism-wise. The anime averts this by giving Kaede a more mature design with a much bustier figure and wider hips, along with her make-up, accessories, and hair being more obviously outlandish, and combining her movements with music, sounds, and voice acting to better emphasize her playfully mischievous side.
• Nice Girl: Friendly, non-judgmental and always happy to lend a hand - Kaede is easily one of the nicest characters in the series.
• Not So Above It All: She refuses to wear leggings in a short skirt during winter because good fashion sense requires sacrifices.
• "Not So Different" Remark:
  • Kaede notes to Miyo during their beach trip planning that, like her, she used to be embarrassed of having developed such an attention-grabbing figure in middle school and tried to hide it.
  • After Mahiro makes a joke about finding momiji (a type of maple leaf) to an unamused Momiji, Kaede notes to Mihari she and Mahiro have similar humor involving tree leaves and their friends' names, with a flashback showing Mihari trying to make a joke about finding kaede (another type of maple leaf) to a similarly unamused Kaede.
• Only Sane Man: Amongst the rather quirky group of oddballs that make up Mahiro and his friends, Kaede is consistently portrayed as the most responsible and levelheaded member, always willing to lend a hand and act as the responsible older sibling for all the activities they do together.
• Rose-Haired Sweetie: While she has red hair in the manga, the anime changes her hair color to pink. It still fits her, being an upbeat and friendly Cool Big Sis.
• Supreme Chef: She can advise Mahiro on how to make something as simple as rice porridge, supervise Miyo in making a delicious birthday cake, can barbeque various meats, and even make pumpkins/squash dishes in such a way that Mahiro, who explicitly says he doesn't like them, finds the meal delicious.
• Taught by Experience: She knows what it's like to have to come to terms with growing into an absurdly mature figure in middle school, so Kaede is able to show the similarly early blooming Miyo how to dress stylishly while drawing attention away from her breasts, but also encourage Miyo to own it as her weapon instead of hiding away her sexy body.
• Tomboy and Girly Girl: She's the Girly Girl to her younger sister Momiji's Tomboy, being a fashion-obsessed, makeup-wearing Gyaru Girl while Momiji is more tomboyish and doesn't like wearing feminine clothing.

Momiji Hozuki

The Best Friend

Voiced By: Minami Tsuda

Kaede's younger sister, and Mahiro's closest friend (and possibly more). Momiji befriends our while out on a shopping trip and later becomes instrumental to getting him back into middle school.

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• Accidental Pervert:
  • During her first visit to Oyamas' house, she ends up falling on top of Mahiro and gropes his breasts trying to push herself up.
  • She grabs Mahiro's privates while roughhousing in a hot spring.
• Adaptation Dye-Job: Downplayed; the anime adds blue highlights to her brown hair.
• Adaptational Nice Girl: Due to the anime changing how scenes like the Porn Stash discovery and the Halloween panic play out and moving the hot springs trip to much later on, Momiji ends up being presented as less judgmental and suspicious of Mahiro early on, as well as making her crush on him slightly more obvious.
• Animal Motifs: Mahiro first compares her to a Kokeshi doll before backtracking and instead comparing her to a bear for her soft-heart and reliable nature. Asahi chimes in by saying it matches her ferocity, to which Momiji promptly clocks her over the head for.
• Berserk Button: Momiji takes great offense at being given outright masculine comparisons, as she gets quite angry over Asahi’s nicknames comparing her to a samurai and clocks her over the head for comparing her to a ferocious bear.
• Bring My Brown Pants: Unlike Mahiro, her accidents are usually caused due to her being startled rather than just plain holding it too long. She among the cast has wet her pants the most amount times besides Mahiro himself.
• Chuunibyou: After Mahiro puts her into a Gothic Lolita outfit, she discovers a fondness of the dramatic. That said, it's downplayed since she doesn't become as obsessed with being "cool" as most examples and it only occasionally resurfaces afterwards, such as when she comes to school wearing an eyepatch (claiming it's her "lucky item"), dresses as a samurai on the New Year's, or gives her MMO character an over-the-top name.
• Comically Missing the Point: She completely misunderstands what Miyo is saying when she warns that your body will redirect its fat reserves to specific body parts if they start to get too cold, and it's heavily implied she used this information to pull the same stunt as Mahiro to try and make her breasts grow.
• Embarrassing Nickname: Asahi gave her a very masculine nickname, "Momijiro", because she thought Momiji was a boy when they first met. Momiji is noticeably annoyed whenever she is reminded of this.
• Hair-Trigger Temper: She’s polite and considerate most of the time but is the most likely to get annoyed by her friends and sisters' antics and has a tendency to show a small degree of aggressive or judgmental behavior towards something she doesn’t like.
• Irony: She’s the least traditionally feminine girl of her friend group and the most vocal in objecting to participating in otherwise girly activities, yet she takes the most offense to having masculine attributes applied to her, and outright smacks Asahi over the head for cracking a joke over her ferocious attitude.
• Never Heard That One Before: Mahiro's joke about finding momiji (maple leaves) to Momiji falls flat because Asahi has already long since run that joke into the ground.
• Nice Girl: Just like her sister. She makes fast friends with Mahiro when she finds him having a panic attack, checks his temperature to see if he's sick, and stays to help with his shopping.
• Precocious Crush: It's pretty clear her feelings for Mahiro are more than just platonic. Of course, she has no idea that Mahiro is technically older than her.
• Tomboy: While Momiji will wear girls clothes out of necessity (her school uniform, for example), she much prefers to wear boyish clothes, as she finds them more comfortable.
• Tomboy and Girly Girl:
  • The Tomboy to Mahiro's Girly Girl. While Momiji prefers boyish clothes, and is often mistaken for a male, Mahiro enjoys more feminine clothing and is more emotionally delicate.
  • She's also the Tomboy to her older sister Kaede's Girly Girl, as Kaede is a fashion-conscious, makeup-wearing Gyaru Girl while Momiji decidedly isn't.
• Tomboyish Ponytail: She wears her hair in a small ponytail, fitting her tomboyish personality.
• Tsundere: She’s generally warm and polite to Mahiro right from the get go, but still has some rather harsh opinions on his lazy habits and after some of his more questionable moments is clearly suspicious of him early on. She largely drops this either after the hot springs trip (manga) or spending more time with him (anime) and becomes more open to doing just about anything with Mahiro, even letting him dress her up in cute feminine clothes despite her embarrassment.
• Why Did It Have to Be Snakes?: She is extremely bad with ghost stories, even very silly ones, which leads to several Potty Failure moments.

Asahi Ohka

The Dog

Voiced By: Kana Yuuki

A classmate and friend of Momiji's. She meets and befriends Mahiro without hesitation during their first get together at a local cafe. Asahi is an endless ball of energy that Mahiro's initially put off by, but her honesty and enthusiastic nature quickly endears her to him as he finds her blunt acceptance of him being a lazy slacker relaxing to be around.

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• Accidental Pervert:
  • In chapter 28, she gropes Miyo's boobs by mistake while trying to wash her armpits.
  • She flashes her older brother at home when walking out of the bath naked on a regular basis.
• Animal Motifs: She's outright referred to as a dog several times, is sometimes drawn with doggy ears and a tail when she gets excited, and the other girls even give her head rubs on occasion.
• Book Dumb: She gets poor grades in school and often neglects or forgets to do her homework. She's had to do makeup work over at least one of her school breaks because of it.
• Cannot Keep a Secret:
  • She tells Mahiro during their first real conversation that Momiji thought he was just extremely lazy, with Momiji and Miyo's reactions making it obvious they weren't planning to tell Mahiro that part.
  • The only reason she didn't blurt out she was a part of planning a secret birthday party for Mahiro to his face was that Momiji and Miyo made her promise, and she immediately ran away.
• Character Tic: She often uses the phrase "tashika ni" (indeed/for sure), and makes a motion mimicking crab's pincers when she does ("kani" meaning "crab").
• Comically Missing the Point: Asahi's takeaway from Miyo's warnings about the cold making parts of you fatter to protect your body is that Miyo goes around topless all of the time.
• Cute Little Fangs: She has a small fang which is often visible even when her mouth is closed, fitting with her fun-loving and energetic nature.
• Deliberately Cute Child: Downplayed as she's a genuinely nice and honest person, but she's well aware of reactions she gets from people and not above taking advantage of them. For example, she frequents a WcDonald's where Kaede is part-timing to get freebies, and visits all her friends' houses on New Year's day for traditional gift money.
• The Ditz: As nice and friendly as she is, she's not very bright. She regularly struggles with her grades, doesn't understand the concept of modesty, and tends to impulsively do or say things without considering the consequences.
• Genki Girl: She's a hyperactive ball of energy that excels in anything physical, is always eager to go off on random adventures or activities, is straightforwardly honest, and friendly with everyone she meets.
• Innocent Fanservice Girl: Asahi off-handedly mentions she doesn't wear much underneath her skirt right before showing off her legs. She's not even put off by having to get topless for the annual physicals. She's actually worse at home as there she's an outright casual nudist that walks out of her baths wet and naked, much to her older brother Yuuya's horror.
• Innocently Insensitive: A combination of honesty, idiocy, and a desire to help sometimes cause her to say or do things she probably shouldn't.
  • She casually admitted to Mahiro that Momiji thought he was just a lazy slacker rather than sickly during their introduction conversation.
  • When Mahiro has to go to the bathroom during their second year opening ceremony and tries to subtly get the teachers attention to sneak off, Asahi straight up shouts out loud that she needs to use the restroom with a smile and thumbs up, much to the students, staff, and especially Mahiro's embarrassment.
  • On at least two separate occasions she's unintentionally made her brother out to be an incestuous pervert towards her when making questionable comments about their bathing routines together.
• The Nicknamer: She comes up with nicknames for most of her friends: Mahiron for Mahiro, Miyochin for Miyo, Momijiro for Momiji, Nayutan for Nayuta, and Doctor or Professor for Mihari. Kaede is the only exception, being called just "(Momiji's) big sister".
• Significant Birth Date: Her birthday, May 5th, is known as Children's Day in Japan, fitting her childish personality.
• That Came Out Wrong: She states her reason for not being embarrassed to go topless during the physicals is that her older brother stares at her when she's naked. Mahiro concludes that Asahi's older brother is peeping on her in the bath, when what she actually meant is that he catches her coming out of the bath naked and yells at her to put clothes on. When Mahiro later blurts out that it isn't right for Yuuya to peep on her, it prompts Asahi to clarify he doesn't peep on her. She's still confused as to why Mahiro ever thought he was.
• Tomboy with a Girly Streak: Asahi is mainly the sporty outdoorsy type and tends to end her sentences with the masculine particle "da zo", but unlike Momiji she never once complains over getting dragged into more feminine activities and generally enjoys doing girly things even if she isn't especially familiar or interested in them.

Miyo Murosaki

The Lily

Voiced By: Natsumi Hioka

A classmate and friend of Momiji's. She meets and befriends Mahiro rather politely during their first get together at a local cafe. A massive Yuri Fan and soft-spoken oddball in her own right, Miyo wins over Mahiro's friendship mainly just by being nice and understanding to him, as he finds her lack of judgment towards his lazy habits to be a relief.

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• Advice Backfire: She tells her friends that your body will deposit extra fat to areas that are colder for extra insulation to deter them from going bare-legged in skirts during winter. Asahi concludes this means Miyo has such large breasts because she goes topless all of the time, which leads to Mahiro attempting to use cold winter winds to make his breasts grow, and it's implied Momiji did something similar to Mahiro to try making her breasts bigger.
• Animal Motifs: Mahiro has compared her to a rabbit for her cuteness and constant horniness.
• Beware the Nice Ones: Incredibly shy, awkward, and friendly, yet on two separate occasions she's gotten onto both Asahi and Yuuya in a very unnerving manner for almost ruining the romantic angle of Mahiro and Momiji's relationship.
• Buxom Beauty Standard: Miyo comes around to the mentality of taking pride in the large size of her breasts somewhat after a heart-to-heart with Kaede about how she shouldn't feel embarrassed of them, and she shows up to the beach trip wearing a revealing two-piece bikini.
• Cordon Bleugh Chef: She has a reputation of making some truly appalling food dishes. Momiji's comments and her being up to bake a genuinely delicious birthday cake under Kaede's supervision indicates that she can cook just fine but starts going off the books from too much excitement over being able to make food for her friends.
• D-Cup Distress: She is incredibly embarrassed by her large breasts and is always thankful when her outfits can successfully hide how big they are. She manages to come out of her embarrassment a little by showing up to the beach trip in a daring bikini on Kaede's encouragement to make her breasts her own weapon rather than hide them.
• Flower Motifs: Lilies are used around or in reference to her multiple times throughout the story as really obvious symbolism to her being a blatant lesbian.
• Girl on Girl Is Hot: She is a firm believer of it, usually giving a light blush over potential female-on-female romance or when reading her yuri manga, and a drunk Mihari aggressively kissing Kaede is enough to freeze her in ecstasy over the sight.
• Hidden Buxom: Miyo's breasts are surprisingly stacked for her age and she goes out of her way to wear outfits that hide this fact out of embarrassment. She and Kaede bond over the latter helping her to invoke this by picking out a swimsuit that hides a lot of skin and draws attention away from her breasts.
• Lipstick Lesbian: She predominantly enjoys feminine activities the most, has a comical obsession with yuri media, and is unambiguously only attracted to girls. Being the "victim" of an off-screen make-out session from a drunk Mihari has her devolve into a quivering mess and dreamily referring to her as Onee-Sama after the fact.
• Nice Girl: Excluding Kaede, she's the most considerate, understanding, and downright polite person of Mahiro's friend group.
• Open Secret: She believes no one notices just how much of a Yuri Fan she is. Mahiro is left dumbfounded by how she could possibly think that when she makes it obvious to everyone.
• Reluctant Fanservice Girl: Miyo is often put into outfits that are either too tight or revealing, or situations that expose just how large her breasts are. Kaede picks up on this during their beach planning and helps her pick out a swimsuit that makes her feel more comfortable to wear one.
• Shipper on Deck: She's firmly on board with Mahiro and Momiji being a couple and doesn't take threats to it lightly.
• Skewed Priorities: She tells her friends they shouldn't go bare-legged in skirts during winter because their legs will get fat, rather than the more obvious health concerns.
• Textile Work Is Feminine: She's the most feminine of Mahiro's peers, and she is good enough at sewing that she joins in to make uniforms for the class's maid cafe and offers to make cosplay outfits for Mahiro.
• Throw the Dog a Bone: Kaede gives her advice on how she shouldn't be embarrassed of her large breasts or mature figure and that she should own it instead of hiding it away. In the end, Miyo has Kaede help her go pick out a more daring bikini for the beach trip and she manages to avoid any embarrassing wardrobe mishaps just from confidently showing off instead of hiding her figure.
• Transparent Closet: She's very unambiguously a lesbian, but believes no one notices it or her love of yuri shipping in general. She's even outright bribed Mahiro to help keep her “secret.”
• Yuri Fan:
  • Virtually any time she sees two girls doing something that she can interpret as having romantic overtones she either asks if it's what it looks like or just assumes it is and starts watching intently.
  • This extends to her tastes in media as she regularly reads Yuri manga and when Mahiro tells her that there's nothing wrong with her fantasies and asks her for some good suggestions, she immediately gives him multiple manga to purchase without hesitation.

Nayuta Tenkawa

The New Girl

A mysterious girl that befriends Mahiro during his second year of middle school. Unlike most people, she's actually already aware that Mahiro is a man turned adolescent girl because she was sent in by Mihari's faculty adviser to keep an on him and Mihari's project with him.

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• Bait-and-Switch: When Mahiro's comrade returns for the third time in the middle of school, she explains to Mahiro that she will ensure his comrade won't be able to accidentally rise to attention and expose him in a suggestive manner that makes him think she's offering to have sex with him. Then she pulls out the duct tape.
• Breast Expansion: During Nayuta and her friend's trip to the beach, she accidentally drinks the "only lasts an hour" temporarily gender bender potion and grows bigger boobs. Nayuta's friends coming back for snacks forces her to wear a jacket for most of it and then later go into the water to hide this fact.
• The Comically Serious: Whether it be learning how to swim, playing games with her friends, or firmly tucking away Mahiro's comrade with duct tape, she goes into every situation, no matter how normal or absurd, with a levelheaded straight forwardness.
• Crazy-Prepared: She carries various small items like tissues, cough drops and spare panties to help people around her with minor problems.
• Fake Boobs: The temporary gender bender potion wears off and her boobs start to shrink in front of Momiji and Asahi right as they catch sight of her suddenly larger assets. This allows Mahiro and her to play it off as having been just a prank.
• Nice Girl: She actively goes out of her way to help make sure Mahiro being a boy-turned-girl stays a secret and that the experience of being a girl is comfortable for him. She's also nice in general to her other friends, often hoping she isn't a bother and wanting to get to know them better.
• Secret-Keeper: She knows from the start Mahiro is actually an adult male in a teenage girl's body and helps him to make sure it stays a secret.
• Super Drowning Skills: Nayuta doesn't know how to swim and even with safety items she's prone to ending up in situations where she ends up losing them or with her head underwater while still wearing them anyway.

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