The Nihon Uma Musume Training Center Academy—better known as Tracen Academy.
From every corner of the country, promising young Horse Girls knock on its gates. It is Japan's premier institution for the elite. Located in Fuchu, Tokyo, this massive boarding school houses nearly two thousand students across its middle and high school divisions.
Inside one particular room—the President's office—three figures stood in a tense silence.
"Confirmation! I wish to respect your autonomy, but I must ask one more time! Are you absolutely certain you want her to be your trainee!?"
As she spoke, the girl snapped open a folding fan with a sharp clack.
Though petite, she wore a striking ensemble—a blend of a navy suit and a white dress—that commanded authority. This was Yayoi Akikawa, the President of Tracen Academy. Her chestnut hair, long enough to reach her thighs, was streaked with a single shock of white. Despite being indoors, she wore a formal hat, upon which a cat sat perched for reasons known only to her.
"We don't expect a rookie Trainer like yourself to manage a full team right out of the gate," added another woman, her voice tinged with hesitation. "Our hope was for you to take on one or two girls in a near-exclusive capacity to gain experience. But, regarding her… well..."
This was Tazuna Hayakawa, the President's secretary and right hand.
Unlike Yayoi, she wore a professional green suit. Yet, she too wore a hat, and her expression mirrored the President's concern as she looked toward the third person in the room.
"It won't be a problem," the young man replied firmly.
He was dressed in a crisp suit, the image of a professional. He was of average height and build, with features that weren't exactly handsome, but weren't plain either—the kind of face you'd pass in a crowd and forget an hour later. His suit was immaculate, and while he didn't leave a strong impression, he carried an air of clean, quiet competence.
He was a rookie Trainer, assigned to Tracen Academy only this year.
Given the sheer number of students, the Academy employed a vast roster of Trainers. He was just one of the newest recruits, yet less than two weeks into his tenure, he had been summoned to the President's office for a private interview.
The topic: the Horse Girl he had chosen to lead.
As a Trainer, his duty was to develop talent. Despite his rookie status, he held a central Trainer's License; on paper, he was perfectly qualified.
Perfectly qualified—and yet.
"Concern! Since we have welcomed her into this Academy, she requires a Trainer! However, for a novice like you to take her on is somewhat—"
"It won't be a problem," the man repeated, cutting Yayoi off with a polite but firm tone.
A confident smile played on his lips as the rookie Trainer spoke the name of the girl he had committed his career to.
"—After all, she's Haru Urara."
Upon hearing his answer, Yayoi and Tazuna could do nothing but twitch their cheeks in awkward, lingering silence.
I don't clearly remember how I died, but it seems I was reborn. I have memories of living well into my mid-twenties, yet when I opened my eyes, I was trapped in the body of an infant.
To make matters stranger, I had been born into a world that was slightly—no, massively—different from my previous one.
The realization only hit me once I'd grown enough to actually process thoughts.
I spent most of my days sleeping, waking only to be nursed by a mother younger than my former self, or to wail in frustration after my body did… well, what baby bodies do. It was an endless cycle of indignity. Then, one day, something on the television told me exactly how far from Earth I really was.
"Shinzan is taking the outside! Shinzan moves to the far outside! There she goes! Shinzan has taken the lead on the outer rail!"
The man's voice was electric with excitement. I looked at the screen, and I nearly choked.
The "athletes" sprinting across the screen were young girls with animal ears growing from the tops of their heads. And it wasn't just ears; they had tails sprouting from their tailbones, swaying and whipping in rhythm with their gallop.
"Shinzan hasn't pulled away yet! Will she make it?! She's out! She's clear! Shinzan takes the gold! Shinzan has achieved the Five Crowns!"
The announcer's voice hit a fever pitch as a roar erupted from the crowd. I stared at the screen, my eyes bulging in sheer disbelief.
(What is this show? Girls with ears and tails… running? The play-by-play is professional grade, but are those spectators extras? Did they rent out an entire racecourse for this? Japan is really going off the deep end.)
I wondered how much the production budget was. At the same time, I tilted my wobbly baby head, wondering who the target audience for this could possibly be.
"So, Shinzan won after all..." my new father mused, nodding sagely.
"She really is in a league of her own," my mother agreed.
I wanted to ask them if they were actually taking this seriously, but a talking baby is the stuff of horror movies. I stayed quiet and watched. After the "race," the mysterious girls gathered on a special stage. Suddenly, a pop song started playing—a catchy, high-energy earworm—and they began to dance.
In the center was the girl called Shinzan. Flanking her were the second and third-place finishers, performing a sharp, synchronized routine. They were beautiful—the kind of idols who would make real-world stars retire out of shame—singing and dancing while the crowd went wild with glowsticks. The energy in the stadium was suffocatingly intense.
By the way, what the hell is a "Umapyoi"? Everyone was screaming it, but I was lost.
"…Impressive," Dad grunted.
"'Impressive' nothing," Mom shot back, narrowing her eyes. "I'd like to know exactly what part of them you're finding so impressive."
Watching my father's sheepish smile and my mother's rising irritation, I had one final thought:
This world is definitely weird.
That was the catalyst. From then on, I started noticing the cracks in the reality I thought I knew.
I was born in a country called Japan, on a planet called Earth. Or so I thought.
But every time I turned on the TV, there they were: "Horse Girls." They were everywhere—racing, being interviewed, or being featured in documentaries like the one I saw on Shinzan.
Watching a news anchor discuss a girl with cat-like ears as if it were the most mundane thing in the world was a sensation I can't quite describe. In my past life, otaku culture had become mainstream, but this was different. This was fundamental.
(What… what are they? Are they a new type of idol group? Some kind of subspecies?)
I wasn't an idol expert in my past life, but was this the new "normal"? Was making girls with ears and tails run a national pastime? Or was I not actually reincarnated? Maybe I was just lying in a hospital bed somewhere, dreaming a very long, very specific fever dream.
A few days later, my parents took me outside. That's when the truth literally ran past me.
A girl—no, a toddler—walked by. She had animal ears and a tail. She was laughing, her ears twitching with joy and her tail wagging excitedly as she held her parents' hands.
(Wait. Are those real? The ears? The tail? Not toys? And wait… she doesn't have human ears on the side of her head...)
Before I could process the ethical implications of "ear toys," a sound like a localized gale tore through the air. A teenage girl with animal ears was sprinting down the side of the road at an impossible speed.
She overtook the cars as if they were standing still and vanished in seconds. I looked down from my mother's arms and saw a narrow lane next to the road. It was marked with a silhouette of a running woman with ears and a tail—a variation of the emergency exit sign. Next to it was a speed limit: 50km/h.
The speed limit for the cars was 40km/h. Nothing made sense.
"Whoa, that girl was fast. I wonder what school she's from?" Dad remarked, impressed but not surprised.
"With that uniform, she must be from Tracen," Mom replied casually.
My parents were the ones I didn't understand. 50km/h is faster than an Olympic sprinter, and if that was the limit, she was likely capable of much more.
Was this a world where aliens and humans coexisted? Was this a fantasy world that just happened to look like Earth?
My brain began to overheat from the sheer confusion. I did the only thing a baby could do: I burst into tears and soiled my diaper. It was a total system collapse.
They weren't aliens. They were "Horse Girls."
They weren't just a gimmick or an idol brand; they were a biological fact of this world. In this reality, horses don't exist. Horse Girls do. On the surface, they look like beautiful human girls with ears and tails, but they are a distinct, albeit similar, species.
The moment I was old enough to speak, I grilled my parents for information. I learned that the race I saw on TV was the Arima Kinen. Horse racing—or rather, Horse Girl racing—was the world's premier form of entertainment.
(Wait, the Arima Kinen… that's horse racing. I mean, I don't know much about it, but that's definitely it. Though the kanji for "horse" looks a bit… off.)
I noticed it when looking at my dad's recorded races. The character for "Horse" (馬) usually has four dots at the bottom, representing four legs. Here, it only had two. I suppose that makes sense since they run on two legs. Even common idioms had changed. Instead of "A gift to a horse," it was "A gift to a Horse Girl."