Last month, the Supreme Court ruled that the current law for gender transition is constitutional, though it registered that this law may fail to align with our current society. The law requires people wishing to change their official gender to be unmarried, have no minor children, be surgically sterilized and have been diagnosed with gender dysphoria.
This decision is painful to see for trans people. I myself am a U.S. citizen with permanent residency in Japan. I changed my gender marker in the United States, which I could not have done here as I don't satisfy all the aforementioned conditions set by Japanese law. The current requirements are physically intrusive, in that the government requires complex and life-altering surgeries; the situation is reminiscent of various laws from throughout the 20th century that required some Japanese people with disabilities to be surgically sterilized, which were only revoked in 1996. The time is ripe for change, as has already happened in many countries, for example as in France in 2016.
What about the other conditions? Should one be required to be unmarried and have no minor children to officially transition? The court justifies this as avoiding confusion within families. The rationale appears to be that children cannot understand a parent's change in gender, and that transition is impossible within a marriage; but as a married person with minor children who has recently transitioned, I can attest that human beings are quite capable of understanding each other's changes — even, fortunately, within families.