Can’t Quite Be Your Sister: Looking at the Japanese laws relating to gender identity disorder

By: Anime Feminist March 15, 20230 Comments
Mahiro makes a big X with her arms as her eyes are squinted together in displeasure. A big blue X is behind them.

This is a translation of a Japanese blog post originally published by popular blogger Honeshabri on Feb. 12, 2023. Anime Feminist requested and received permission to translate and reproduce the post. Translation was provided by Chiaki Hirai.

Editor’s note: Given the debatable state of Mahiro’s gender at any given time after they are physically turned into a girl, this article uses they/them pronouns for them.

One day a man awakens as a beautiful girl.

However, legally, they remain a male.

Is it possible to have their gender marker amended?

One who transitions

A guy who lived his entire life as a man one day finds himself turned into a girl by way of some strange circumstances. Happens to all of us. And Oyama Mahiro from this season’s Onimai!: I’m Your Sister Now is one such person. Although he was once an adult male, he wakes up one morning as a girl.

A young girl plays a handheld video game concole, a handwritten star reads their name is Oyama Mahiro
“Onimai!: I’m Your Sister Now” OP

Mahiro finds himself in this predicament because of his little sister Mihari. A genius capable of skipping several grades and is now a graduate student, she drugs an unwitting Mahiro with a concoction she developed.

Normally, if an adult male gets turned into a little girl, they would have a lot to deal with. You’d have to ask questions like, what do you do about work? However, Mahiro luckily doesn’t have to worry about those concerns. That is because he is a hopeless hikikomori NEET who loves porn games and hasn’t stepped outside in two years.

If anything, Mahiro’s transformation into a girl was nothing if not a positive for them. That is because the transformation provided freedom from pressure. Mihari was not only smart, but also athletically gifted enough to break records in track and field. As the elder brother of such a gifted sister, Mahiro must consider his place, as well as his appearances to those around him. He felt oppressed with expectations. Those burdens caused him to become a recluse in the first place.

However, things are now different. By taking on the appearance of someone younger than their sister, they no longer have to be in a position above their little sister. Free from that expectation to succeed, they can now challenge themselves on their own terms, and they can also rely on their sister for help. It is only thanks to Mahiro’s transformation into a girl, that they are able to start on a journey toward reentering society.

Translation: An “older brother” who became a shut-in because of his overly gifted little sister one day awakens as the “little sister.” 
This is a socially aware porno anime that grants emotional care by making it socially acceptable to look up to a younger sister. 

Of course, there are issues with an adult male living as a young girl. Mahiro initially feels uncomfortable looking and dressing like a girl, and was also traumatized experiencing their first period. But as time goes on, they gradually get used to it all. Whether it’s their psyche reorienting itself to fit their body or an effect of the drugs, Mahiro just naturally accepts various aspects of living as a girl. So much so that, after their sister pulls some strings, they get enrolled into middle school as a girl

Mahiro nervously smiles while standing in front of a blackboard. Their name is written behind them.
“Onimai!: I’m Your Sister Now” Ep. 6

At this point, viewers must think: “Wouldn’t they just be happier if they lived as a girl for the rest of their life?” That drug is powerful enough to let them do just that. In just one night, it managed to turn Mahiro into a complete woman1, one that can menstruate and continues to work several months on2. Not only that, they’re psychologically becoming a girl too, so nothing is really holding them back. By continuing to take this drug, they can happily live as their little sister’s little sister

However, there is something even this perfect and powerful drug cannot change. And that’s the family registry.

Identity, Body and Registry

I, like most people, am cis gender which means the “gender identity I feel” matches with my “assigned gender at birth.” Although I often face moments where I feel my gender is pertinent, I have very little cause to contemplate what my legal gender is on paper. I am listed under the gender I identify with, and I might not even realize it’s even there half the time.

A sample of a Japanese insurance policy ID card, one line has gender listed amidst the data.
A sample image of a health insurance card from the
Japan Health Insurance Association

For example, insurance cards, passports and My Number Cards all have a gender listed on them. If Mahiro must go to the hospital or leave and enter the country, they’ll need to provide these documents to confirm their identity. When they do, it will become a problem since there would be discrepancies3. In reality, there are transgender people whose presenting gender looks different from their legal gender on paper due to things like hormone replacement therapy and they may be denied medical treatment because of it.

This was an issue before insurance cards even got involved, but when Tanaka Rei suffered from a subarachnoid hemorrhage and stroke in 2003, they were denied hospitalization because of their status as transgender. 

I was then denied treatment from dozens of practitioners. The reason why? I was told “there was no precedent” or that “they need to discuss it” or “they would need to ask the hospital director.” 

Tanaka Rei “The State of Medical Care for Transgender and People with Gender Identity Disorder”

Aside from going to the hospital, they could face issues with marriage and employment. How would they explain the difference between how they look and what the documents state to their employer? And will the employers accept it? For transgender people who have not had their documentation amended, even standing at the startline is a difficult bar to clear in finding work. Can Mahiro do this?

And on the issue of marriage, they would not be able to at this point in time. That is to say, trans women who wish to marry men who have not amended their documentation, and likewise for trans men looking to marry women, are not able to tie the knot because same-sex marriage is not legal in Japan4. While Mihari imagined her brother becoming a bride, that’s not possible with how things are now.

Mahiro in a wedding dress is princess carried by a good looking faceless man. They are bathed in stars and light: I'm so happy.
Episode 4

What should Mahiro need to do to live as a woman? You can’t possibly expect them to just forge documents every time it’s needed, like how they presumably did to enroll back into middle school.

As luck would have it, Japan has a law that allows you to change your gender on your family registry. With this, Mahiro can legally become a woman. However, there is a price for everything and the price for Mahiro would be their uterus and ovaries. You could perhaps call this “equivalent exchange.”

The Stipulations of the Special Act

The law allowing gender changes in Japan is known as the “Act on Special Cases in Handling Gender for People with Gender Identity Disorder” (the Special Act from here on). There are largely three steps toward changing your gender with the Special Act.

  1. A diagnosis of gender identity disorder5 from at least two doctors.
  2. A family court ruling on the gender change
  3. The change of gender

The first step, requiring a doctor’s diagnosis, is essentially to confirm whether your assigned gender at birth truly is different from your gender identity. You can get through this if you set your mind to it. Even if they are trained psychiatrists, they can’t truly tell what you’re thinking deep down. Show your steadfast resolve by saying things like, “I’ve always liked skirts since I was little,” or other things that heavily stress stereotypical expressions of gender6. Mahiro should be able to get through this just fine.

The problem is the second step of the process. In order for the family court to approve the application, the following five conditions must be met.

  1. Be over the age of 18.
  2. To not be presently married.
  3. To not have a minor child.
  4. To not have gonads, or to permanently lack functioning gonads
  5. For the body to possess genitalia that closely matches those of the gender they are transitioning to be.

In Mahiro’s case, the first three shouldn’t be an issue7. They’re originally an unmarried adult male. Skipping over number four, condition five should also be fine. Thanks to Mihari’s drugs, Mahiro’s “little buddy” has disappeared without a trace. Another middle schooler girl could look at them up close and she would be none the wiser8

The problem lies in the fourth condition, “to not have gonads.” In other words, they must not be able to have children9. In Mahiro’s case, as stated earlier, they can menstruate and thus it’s safe to assume they have functioning female gonads. Thus, in order for them to change their gender marker, they must undergo a hysterectomy10. This has to be a mistake, right?

Mahiro makes a big X with her arms as her eyes are squinted together in displeasure. A big blue X is behind them.
“Onimai!: I’m Your Sister Now” OP
Postscript: Feb. 18, 2023

According to Anon, who actually went through gender confirmation surgery, Mahiro would be required to go through an external genital examination and karyotype test before undergoing surgery. Proving that her body is already female, she could probably change her gender marker through a “correction of gender,” without going through the Special Act.
An Anon helps flesh out the Onimai Essay

So if they must get surgery done, another issue comes up, and that is the issue of money.

Surgery costs and Insurance Coverage

So how much is it going to cost for Mahiro to get a hysterectomy? Let’s take a look at the prices listed by G-pit, one of the leading agencies assisting in gender confirmation surgeries.

If the operation is to be done in-country (in Japan), there’s a difference of around 150,000 yen ($1,089 USD) depending on which operations you opt for, but including consultations it should cost a little over 1 million yen ($7,260 USD)11. As for time commitments, it would take around a one night stay in the hospital after the surgery. However, they will need to do some blood work prior to the operation and you will also need to go back to the hospital afterward to get stitches removed and to conduct additional examinations.

If you want to instead get a more skilled gender confirmation surgery than what you can get in Japan, you can opt to have the surgery done in Thailand where the practice is more common. The price will vary depending on the service plan. The cheapest “basic plan” will take 10 days and cost something around 600,000 to 800,000 yen (including airfare) ($4,350 to $5,800 USD)12. However, if they opt to add a more thorough checkup and an extended stay, they would be on the hook to pay those extra charges. Even if they were to choose the “peace of mind plan” without adding additional examinations, it would take 10 days and cost 700,000 to 900,000 yen ($5,000 to $6,500 USD). You might be out of commission longer, but it would be cheaper to do it in Thailand than in Japan.

And there might be some people wondering here. “Is gender confirmation surgery covered by health insurance?” It’s true that, according the 2018 Revised Pricings for Medical Services13, it is covered under health insurance. The out of pocket expense for the procedure is 30% and, combined with the reimbursement system for high-cost medical care, this should be shaved down to under 200,000 yen ($1,450 USD)14. That is to say, you cannot just go to any medical service provider and must go to authorized facilities.

The issue for Mahiro, however, is that their sex changed due to a drug. This drug has not been given regulatory approval. In that case, they had elective treatment for their gender identity disorder. Because of that, Mahiro’s treatment would be considered “mixed medical care” with drug treatments (elective care) + gender confirmation surgery (covered care), and thus all of the treatments would be considered out of coverage.

A man wearing a NEET shirt takes medicine (elective care) and surgery (covered care) and comes out as a happy girl. Underneath there is a note "Mixed Medical Care : Outside of Coverage"
Mahiro’s gender transition included elective care so it is not covered by health insurance

Actual transgender people trying to transition also face similar issues. This is predominantly due to hormone replacement therapy. The Japanese standards of care to treat gender identity disorder largely follows three steps set by the Japanese Society of Psychiatry and Neurology.

  1. A psychiatric diagnosis (counseling and diagnosis by a psychiatrist): covered by health insurance
  2. Hormone replacement therapy (administering hormones to change the body): not covered by health insurance
  3. Gender confirmation surgery (sterilization, labiaplasty and phalloplasty, etc): covered by health insurance

In changing one’s appearance, hormone replacement therapy is more important than gender confirmation surgery15. However, since hormone drugs lack the applicable data to be covered under insurance16, hormone replacement therapy is considered to be elective care. Thus gender confirmation surgery also becomes disqualified from being covered by health insurance. According to a September, 2022 report by the Japanese Society of Gender Identity Disorder, among the 198 gender confirmation surgeries conducted since 2018 in domestic facilities such as university hospitals, only 7 cases (about 3.5%) were covered by health insurance17.

In this way, if Mahiro were to try and become a woman, they would be saddled with exorbitant costs to have a hysterectomy. So how would this go in another country?

The state of the world

On the laws pertaining to changing one’s gender marker in other countries, the report entitled “Laws on Gender Recognition in Japan and other Countries” published by the National Diet Library in 2020 offers a detailed look. Let’s take a look at the state of the world from there.

First within the international community, most countries have ruled requiring sterilization infringes upon human rights. For example, the United Nations bodies such as the World Health Organization issued an interagency statement on “Eliminating forced, coercive and otherwise involuntary sterilization”18 in 2014. Furthermore, the European Court of Human Rights ruled in 2017 that “making recognition of the sexual identity of transgender persons conditional on undergoing an operation or treatment entailing sterilisation – or which would most probably produce that effect –” was a violation of human rights19.

Thus, even among countries that required sterilization to change gender markers, many have reconsidered that requirement in the past 10 years. In Germany, a 2011 ruling by the Federal Constitutional Court ruled it was unconstitutional to require sterilization. Sweden and the Netherlands revised their laws in 2013 to get rid of the sterilization requirement.

For the United Kingdom, which legalized gender marker changes at the same time as Japan in 2004, there’s no requirement for surgery, much less sterilization. Since the policies went into effect, the country has required three things.

  • To be diagnosed with gender dysphoria
  • Live as your new gender for two years
  • Be single.

Seeing this, it’s a matter of course that transgender Japanese people would say the “Special Act infringes on human rights” and sue for reform. However the Supreme Court in 2019 ruled “the sterilization requirement is not unconstitutional.”20 It is important to note, however, that two of the four justices appended a comment stating “While this ruling does not go against Article 13 of the constitution, it undeniably raises questions.” 

Furthermore, in December of 2022, the Supreme Court said all 15 justices of the court will preside over a trial regarding the sterilization requirement21. By the time Mahiro turns 18 a second time, Japan may allow them to become a woman without a hysterectomy22.

Mahiro makes a big circle with their arms. Their mouth also open in a big O. A red circle is behind them
“Onimai!: I’m Your Sister Now” OP

In Closing

In watching Onimai!, I couldn’t help but think. That “it’s hard enough to be transgender already, but to be hit with acquired gender dysphoria (like in Mahiro’s case) seems even worse.” However, I only know transgender issues through articles I read online. Were these thoughts correct? That is why I decided to learn more about transgender people.

I read a number of books, and I confirmed that actual trans experiences greatly differ from Onimai!. Among which, I learned that gender confirmation surgery was something much more taxing than I had ever imagined. I can’t help but think about how many trans women could be helped with Mihari’s drug.

But I realized something as I kept reading over the Special Act. Under the current policy, even if one were to become a complete woman23, they cannot legally be recognized as a woman24.

I am a cis man, and I still don’t really know what it’s really like to have my gender identity and my body not match. However, I can tell that the Special Act is flawed. That is why I have written this article. I am looking forward to see how the Supreme Court will rule going forward.


These are the books I used to write this article. Value Books agreed to sponsor me for these books. For more information, please read my note posting

“Deciphering LGBT: An Introduction to Queer Studies”

LGBTを読みとく ──クィア・スタディーズ入門 (ちくま新書)

A book to learn, not only about transgender issues, but LGBT history as well. While transgender issues have different issues compared to gay and lesbian issue today, many issues on gender identity and sexuality were once mixed and not clearly defined. This is a good book to learn more about transgender history.

“To Gender Dysphoria・Gender Incongruence”


  • By Harima Katsuki
  • Ryokufu Publishing

While it was called gender identity disorder, it’s now called gender dysphoria or gender Incongruence. What’s the difference? This book aims to answer those questions. Starting with organizing definitions, the book discusses the effect of depathologization in an easy to understand way.

“A Trans Man’s Study of Transgender Manhood”

トランス男性による トランスジェンダー男性学

  • By Shuji Akira
  • Otsuki Shoten

A book on the experience of transgender men by a trans man author. As you can see from the title of the book, it is a “study on manhood.” I feel there is less published on trans men in Japan than trans women, so this book helped me to learn a lot more about them.

“Transgender Feminism”


  • By: Tanaka Rei
  • Impact Publishing Group

This is the book by Tanaka Rei, the person I wrote about who was denied hospitalization because of their gender. While Tanaka is “trans masculine”, it’s important to note it’s not so much “they wish to be a man” and more “they do not wish to be a woman.” People are prone to think of gender identity as male and female binaries when discussing transgender issues, but there are people who are neither. This book observes society and the Special Act from the perspective from such a perspective.

“Sex Changers: The Japanese people in the ‘Sex Change Business’”

性転師 「性転換ビジネス」に従事する日本人たち

  • By Ito Ito Genki
  • Kashiwa Shobo

This is a book on the history and state of gender confirmation surgery assistance agencies such as G-pit, which I referred to for the cost of GC surgeries. The author is not trans, but is a journalist who investigated a wide berth of topics and is a solid non-fiction read.


1. While this article states Mahiro’s body is a “complete woman’s”, this is used in contrast to what is achievable through gender-affirming surgery today. While surgery can help a male body look like a woman, they cannot get pregnant. That is why I described Mahiro’s body as a “complete woman.” But, it’s also important to remember that even cis women, for various reasons, may not have the ability to give birth. I am not saying such people are “incomplete women” either, and they must never be considered such.

2. The anime skipped the Hot Spring story, so the effect of the drug was prolonged even more.

3. In the comics, Mahiro has gone to the hospital when they hit their head. They have likely forged IDs to do this.

4. On Nov. 30, 2022 the Tokyo court upheld a ruling that a ban on same-sex marriages was constitutional, but also argued it was unconstitutional for same-sex partners to lack a means to become families. Japan court upholds ban on same-sex marriage but raises rights issue

5. Under the World Health Organization’s 11th revision of the International Classification of Diseases, it is considered a “gender incongruence,” and no longer considered a disorder. However in Japan, it is still known as Gender Identity Disorder and I have matched my description to the law.

6. This is fine for people who would like to change their gender no matter what, but is an issue to people who wish to “remain as they are.” That is to say, just because one might feel they are a woman doesn’t mean they must have feminine hobbies and tastes. Especially so in “Onimai”, there are girls who like to dress boyishly like Momiji in the show.

It’s the same for people feeling gender dysphoria, some people will have hobbies and tastes that don’t necessarily fit with their gender identity. However, that may impede a psychological diagnosis. Someone might argue: “While they claim to be a woman, are they really with that hobby?” Thus, many transgender people tend to self-report in a way to closely as possible mirror gender stereotype for the sake of transition. They must lie about themselves in order to become their true selves.

7. This has nothing to do with Mahiro, but both points 2 and 3 are troublesome. Point 2 stipulating “being single” is due to Japan not recognizing same-sex marriages. If it was allowed, a person could transition after marriage and enter into a same-sex marriage. However, in Germany’s case, back when same-sex marriage was still illegal, requiring the annulment of a marriage to transition was ruled unconstitutional and abolished. Changing one’s gender was considered a “personal right” and prioritized over dodging same-sex marriage rules. In this way, there were same-sex marriages in Germany 10 years before it was formally recognized, and there weren’t any real issues with it either it seems.

On point 3 “to not have any minor children” is apparently due to “eliminating negative influences on parental relations” and for the “welfare of minor children.” When the law was first enacted, there was no limitation on age and it simply read “no children.” While the restriction was relaxed to append “minors” to the law, this is still a pain. The funny thing about this point is that undergoing gender confirmation surgery “has nothing to do with whether someone has a minor child or not.” So, say one has already fully transitioned, they cannot amend their documents if they have a minor child. As I wrote in the article, this will cause issues due to the paperwork not matching up with how one presents, causing trouble at work or other parts of life. If the law was truly looking out for the “welfare of minor children,” shouldn’t it be better to not have this stipulation?

For those who wish to know more about the Special Act’s issues and the need for reformation should read the Science Council of Japan’s proposal (in Japanese).

8. In the manga, they already experienced this as of chapter 18.

9. Since it’s fine if the gonads aren’t functioning, postmenopausal people are exempt from surgery requirements. “How to change gender markers for those with Gender Identity Disorder”

10. Or an orchiectomy for male bodies. 

11. Price sheets for in-country services, G-pit | Transgender Support

12. [Thailand] Price sheets for Female to Male SRS surgery G-pit | Transgender Support

13. 2018 Revised Pricings for Medical Services | Japanese Ministry of Health, Labour and Welfare

14. The coverage of Gender Confirmation Surgery in health insurance |

15. Furthermore, in contrast to gender confirmation surgery which is permanent, hormone replacement therapy can be stopped in most cases. For this reason, most people start HRT before surgery.

16. While hormone medications have been in use for quite some time, there are multiple hormone medications prescribed in different ways. Thus there is not enough data to prove the effectiveness and safety of individual hormone medications. That said, these hormone medications are already mass produced and readily available at reasonable prices, so it is impossible to recoup the cost of testing them today. Thus, with no incentives for pharmaceutical companies to pursue this, they remain outside of insurance coverage.

17. Insurance coverage of gender confirmation surgery at 3%, prior hormone replacement therapy stems spread – The Sankei News

18. Eliminating forced, coercive and otherwise involuntary sterilization (PDF)

19. Information Note on the Court’s case-law 206 (April 2017) (PDF)

20. Details on established precedents | Courts in Japan

21. “Requiring surgery for gender change” possibility for a new ruling from Supreme Court trial | NHK 

22. That is, if the anime takes place between 2022 to 2023. The manga takes place in 2017, so it’s too late there.

23. I‘m repeating myself, but this is in describing a body in contrast to one currently attainable through gender confirmation surgery. I mean no offense to sterile women.

24. Though, as I note in the postscript above, there are other ways to do this.

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