Chapter 1: I Got Sent Flying by an Umamusume
Tokyo – Tracen Academy Affiliated Hospital – Neurology Office
Steam rose from a porcelain teacup as a young woman with short brown hair and long brown horse ears sat behind a desk, holding up an X-ray image of a human brain.
After carefully examining the scan, her red eyes—patterned like half-closed blinds—glinted with visible interest as she looked at the young man seated across from her.
"Hit by an umamusume going dozens of kilometers per hour… and you only came out of it with a soft tissue contusion?"
She chuckled lightly, eyes narrowing in amusement.
"Fascinating. What a strange body you have, Yasui-kun. How about it? Would you like to volunteer for one of my experiments?"
The young man named Makoto Yasui didn't hesitate for even a second.
"No, thank you, Dr. Tachyon. Also… just to confirm, aside from the contusion, I'm completely fine, right?"
Putting down the X-ray, Agnes Tachyon took a sip from her tea and smiled quietly. Her sharp eyes curved as she watched him.
'What an interesting young man…'
A few months ago, Tracen Academy had released the results for the Central Trainer Qualification Exam. As usual, the number of successful candidates was small. But the one who took the top spot had thrown the entire industry into shock.
Makoto Yasui, age 18. Fresh out of the Trainer Academy, barely a year past graduation. And except for the vocal and rhythm segments, he had earned perfect marks across the board.
Even she had been stunned.
Though she had retired early, she had once been an active umamusume herself and understood just how difficult the Central Trainer Qualification Exam was.
Most trainers who passed were in their thirties at the youngest. Even those in their twenties were rare. And someone like this—an eighteen-year-old—was simply unheard of.
She'd wanted to cut him open for research the moment she heard the news.
Ideally, a brain dissection. That could finally push her human physiology project forward…
But between hospital shifts, lectures, and research talks, she hadn't been able to find an opening.
Until now.
Today, the boy had come to her—hand-delivered, so to speak.
After being launched ten meters by an umamusume sprinting at full speed.
Ordinarily, such a collision would've at least left someone with broken bones or internal damage.
And yet, all he had was a minor contusion.
What's more, according to the umamusume who brought him in, after being sent flying he got back up on his own—completely fine, like it was nothing.
That meant it wasn't just his mind that was monstrous.
His body might be, too.
'Now… how should I go about prepping this guinea pig for a dissection? Brain tissue would be ideal. Yes, very ideal…'
As she sipped her tea, pretending to ponder his condition, her mind was already racing with medical justifications.
Makoto could feel her crimson eyes boring into him. A chill crept up his spine.
Something felt very wrong.
He had heard the rumors about Dr. Agnes Tachyon—stories of her obsession with human experimentation.
Though no one had ever proven them, it was hard not to believe when she stared at you like that.
Especially when you were perfectly fine and she still acted like she had a diagnosis to hand down.
But Makoto wasn't just medically literate because of the Trainer Exam's strict requirements.
In his previous life, he'd been an extreme stunt athlete.
"Extreme Stunts" was a fairly new category of athletic competition—a kind of ultra-high-difficulty performance sport.
It incorporated challenging moves from a variety of other disciplines:
Forward tucks and backflips from gymnastics, flying arm locks from martial arts, even double spinning kicks from Capoeira.
And by combining them all, it created something even more visually impressive… and far more dangerous.
This kind of sport, as one might imagine, was extremely dangerous.
And while Makoto had the talent and ability to rise through it with few injuries, a high-altitude stunt went horribly wrong during a performance—an accident involving a flying apparatus.
And just like that… he woke up in another world.
That's when he realized something:
This world was different.
There were no horses in this world.
Instead, there were horse girls—Umamusume.
Girls with long ears and horse tails, born with extraordinary physical prowess thanks to the blessings of three deities known as the Three Goddesses.
They weren't just stronger than humans—they were in a league of their own.
Most notably, their speed.
They have an average running speed of 60 kilometers per hour.
They loved to run.
So much so that entire institutions had been founded for their training—chief among them: Tracen Academy.
In this life, both of his parents were connected to Tracen.
His father was a regional trainer, and his mother, a retired regional umamusume racer.
So, it didn't take long for him to make up his mind.
If, in his past life, his greatest dream was to challenge the limits of the human body, then in this world… it was to witness the most extreme performances possible.
And what better way than to become a trainer for beings who defied human limits?
Umamusume looked human, yes, but their potential far surpassed anything humanly possible.
To Makoto, they were the embodiment of his dream.
He wanted to see just how far they could go.
And maybe—just maybe—through them, he could find a way to push his own boundaries too.
With those thoughts in mind, and the strength of two lifetimes' worth of experience, he enrolled in the Trainer Academy right after junior high.
Fresh out of school, he passed the Central Trainer Qualification Exam and moved from his hometown to Tokyo.
For new trainers, it was nearly impossible to sign a contract with an umamusume right away.
Usually, they would apprentice under a senior trainer, build experience, and only later start teaching independently.
But Makoto was different.
He didn't think he needed to wait.
He wasn't arrogant enough to call himself the best in the world, but he was confident.
As a former elite stunt athlete, his physical and mental capabilities were top-tier.
And with his parents' help, he'd been learning trainer knowledge long before the academy.
He was certain he had what it took to raise a truly exceptional umamusume.
The problem? Nobody else believed that.
In the months since arriving in Tokyo, he had tried to approach several umamusume.
Every single one had turned him down.
And today… was no different.
After being rejected again, his mind had wandered while waiting at a crosswalk.
That's when he noticed a child stepping into traffic.
Without thinking, he moved.
The child was saved.
He got launched.
Not by a car, but by an umamusume.
Black hair, red eyes. Running at full speed.
Fortunately, thanks to his past life's reflexes, he twisted midair, minimizing the damage.
He didn't suffer any serious injury.
He had planned to walk it off, but the umamusume who hit him had clearly panicked.
She apologized over and over and insisted on taking him to the hospital.
He tried to decline, but she wouldn't budge.
She had the look of someone who'd follow him forever if he refused.
So, reluctantly, he came in for a checkup.
And that was his real mistake.
Because while the collision hadn't caused him any harm—coming to the hospital had landed him straight into the hands of Dr. Agnes Tachyon, one of the most infamously eccentric umamusume in the medical field.
And now she was staring at him like she wanted to cut him open.
Makoto sighed inwardly, already scheming an escape plan.
Just then, after staring at him for what felt like forever, Agnes Tachyon finally spoke—slowly, like she was savoring every word.
"Aside from the contusion… hmm, well, it's a bit too early to say."
Agnes Tachyon's voice was calm, but Makoto could already feel the storm brewing behind it.
"After all, some complications might not show up until a few days later. That could be a real problem if we don't catch them in time."
She paused to take another dainty sip of tea before continuing, completely serious.
"So, my professional advice: Yasui-kun, you should stay here for observation. For a while. Maybe a long while."
"And," she added with a disturbingly cheerful smile, "you might need a craniotomy or two. Just to check things properly."
Makoto's scalp tingled.
Yup—no doubt about it now.
She really was trying to cut him open.
He was just about to speak up and firmly reject the idea when—
BANG!
The exam room door slammed open.
A blur of black hair burst through, and with it, a dreadful creaking and cracking sound as the door handle snapped clean off, dragging a chunk of the door frame along with it.
"C-Craniotomy?! It's that serious?!"
The black-haired umamusume blurted out, eyes wide in shock.
Both Agnes Tachyon and Makoto turned toward her, stunned.
She glanced down at the metal doorknob—still clutched in her hand—and then at the new hole she'd just put in the door.
"Ah—s-sorry! I-I got a little carried away…"
With a swish, she quickly shoved the door handle behind her back like she could somehow hide the damage. Then, she bent forward and gave a sharp, apologetic bow.
"D-Dr. Agnes Tachyon! Hello!"
"I-I'm Kitasan Black! I'm a new student at Tracen Academy this year! It's an honor to meet you!"
"And, and— about Yasui-san! I—I'll take full responsibility for anything that happens to him! Anything!"