Miki’s eyes snapped open.

Pink curtains. Stuffed animals.

Rather, Tatsuko’s eyes snapped open.

Here we go again.

For about two months now, Maebara Miki and Teraoka Tatsuko had been experiencing what the internet was calling “Kimi-byō”, or “You Syndrome”. About once a week, the two high school students would wake up in each other’s bodies, an experience that would usually last until they went to sleep at night. The phenomenon seemed to only be occurring in Japan, although there were a few unconfirmed reports from South Korea as well. When the first cases had been discovered, scientists from all over the world had descended on the county hospital where one of the patients had been admitted. Now, it was just one more thing that went on a student’s medical record…making for some very complicated bureaucratic efforts.

Scientists had tracked the explosion of occurrences back to the appearance of Shinkai’s Comet several years ago, but from there they were mystified. In nearly every situation, the affected had been opposite-gendered teenagers, but no one could explain why. The moment of transition had been caught in an MRI…but revealed nothing, leaving everyone as confused as before. But meanwhile, Miki and Tatsuko both had classes to attend, just like the eighty or so other known cases of kimi-byō. So life went on.

Except today…something was wrong. He felt sticky, as if he had been sweating through the night, and he was aching in little bits and pieces all over. Miki lowered his hands to his…to Tatsuko’s stomach, which seemed to be hurting from the bottom, if that made any sense. Food poisoning? he wondered. What did she—

He groaned involuntarily. The cramping sensation had gotten much worse as he tried to sit up, Tatsuko’s large sleepshirt shifting around him. Spitefully he glared downward—

And froze. There was a reddish blot on the bottom sheet, near the depression where his—her hips had been.


With a yelp Miki leapt out of the bed, almost sprawling on the floor when his foot got tangled in the blankets. His heart was racing, and the pain in his…stomach…spiked in response. His forehead throbbed in sympathetic torment. Oh crap, oh crap. Is Tatsuko sick? …Is it something serious? Am I going to have to go to the hospital? I have a history test today!

Hey, you can’t get diseases through kimi-byō, can you??

“Tacchan?” Tatsuko’s mother called. “Is everything okay?”

“Y-yeah!” Miki replied, feeling a blush rise to his cheeks. Why did he blush so much more easily in Tatsuko’s body? “And it’s Miki today,” he added, a little apologetically.

If Tatsuko really is sick, I’ll have to tell her mother…

“Oh, Miki-kun,” came the response, noticeably cooler. “Irasshai.” Pause. “You’d better be on your best behavior.”

“Yes, Teraoka-san,” Miki called back. She said that every time, every time since he and Tatsuko had agreed to tell their parents what was going on. Miki was pretty sure Tatsuko had gotten the better end of that deal; she was calling his parents “aunt” and “uncle” by now.

I guess parents really are more protective of girls.

His abdomen chose that moment to cramp up again, and Miki leaned forward a bit, hands on his—


Oh no.

No no no no…

Miki picked up Tatsuko’s phone.

This can’t be happening.

As usual, there was an email, from teraoka_tatsuko@​yahoo.co.jp to teraoka_tatsuko@​yahoo.co.jp. Unread. They never knew when they were going to switch next, so they had gotten in the habit of sending updates every night, just in case.

Please, Tatsuko-san…

Miki opened the message.

Morning, Miki-kun! 😊

Should be just a usual Friday tomorrow, except we have that assembly for Foundation Day in the morning. My shift is 6-9, so you’ll have to eat dinner early in order to make it to the store on time. I let Mom know already.

You have your history test, right? Good luck! ⭐️ ⭐️ ⭐️

And, um…you’ve probably noticed by now.

You know, no one ever talked about this on the forums.

I guess it was bound to happen sooner or later. You missed it last time but that wasn’t going to happen twice. I would say I’m sorry, but I’m not sorry to have a day off this month. I think you’ll understand afterwards. 😉

Make sure there’s at least eleven or twelve pads in my school bag—

Eleven or twelve??

—I’ve never needed that many but trust me, it’s better than the alternative.

Shibata-sensei is the worst. You’ll probably have to say “feminine problems” to get him to let you go to the bathroom—you’d think he’d get it after teaching high school his whole life. The rest of the teachers usually get it.

Good luck, Miki-kun. And if you want to complain, remember that girls are expected to do this every…single…month. Just go about our days as if everything is normal, even though…

Even though it feels like someone’s punching me in the…


Or maybe it’ll still be me again tomorrow, and through the end of it, and you’ll get lucky again this month. Guess we’ll see.




The second postscript was a URL. Miki tapped on it; the page that came up was titled “How to get blood out of fabric.”

He groaned again. Today was not going to be fun…

I got this idea shortly after watching Kimi no Na wa last year, but never quite got around to writing it until now. My original idea was for Miki to have NO IDEA what was going on, and end up staying home all day freaking out, but I decided that was too unrealistic—not necessarily for a teenage boy to be that oblivious, but for Tatsuko to not see it coming the second month they were switching bodies. (There’s a chance she’d be too embarrassed to mention it, or at least more than she is here, but I think that would make for a worse story, so *hand-waves* artistic license! She’s just a very progressive girl.)

Oh, and for what it’s worth I don’t think Miki actually blushes more in Tatsuko’s body. It’s probably just a combination of getting a chance to reset his personality, and having more to blush about on top of that.

Please don’t take the Japanese setting too seriously. That’s mostly there to reference Kimi no Na wa. (That said, bonus points if you pick up all the references in everybody’s names.)

Thanks to my friend S for giving me feedback on an earlier draft, and for answering some questions about periods that I couldn’t find good answers to searching online.

I actually have a few other ideas for Kimi-no-Na-wa-style bodyswap fiction, so you may see a few more of these stories go up in the future. None of them currently involve menstruation, though.

Hm. I have coworkers who read this blog.