Chapter 1
Tokyo — Tracen Academy Affiliated Hospital, Neurology Examination Room.
Behind the desk sat a woman with long brown ears and short brown hair. She was holding a steaming cup of black tea in one hand and a brain X-ray film in the other.
After examining the X-ray for a moment, she looked up at the young man sitting across from her. A clear spark of interest flashed in her reddish eyes, which were marked with horizontal slit-like pupils.
"Getting launched 10 meters by a horse girl running at several dozen kilometers per hour… and the only injury is a minor cartilage contusion?
"Hohoho… What a fascinating physique…
"Would you be interested in becoming my test subject, Yasui-kun?"
Sitting opposite her, the young man named Yasui Makoto shook his head rapidly without the slightest hesitation.
"Please excuse me, but I must decline, Dr. Agnes Tachyon."
"Also… besides the contusion, I don't have any other issues, right?"
Dr. Agnes Tachyon set down the X-ray, cupped her red tea with both hands, and took a slow sip. She narrowed her eyes and the corners of her mouth curled upward.
How very interesting… this young man…
A few months ago, the academy had released this year's Central Trainer Exam results.
As usual, not many people had passed. However, the person who took first place had shocked the entire industry.
Yasui Makoto, 18 years old. He had only graduated from the Trainer Academy last year. Apart from the vocal performance (singing and dancing) section, he scored full marks in every subject.
Even Agnes Tachyon had been astonished by that.
She had retired early, but she had once been an active horse girl herself and knew exactly how difficult it was to obtain a trainer's license — especially at the Central level. Passing it was no exaggeration to say one in ten thousand.
Most trainers who earned the license were over 30. Those in their twenties were extremely rare, let alone someone doing it at the unthinkable age of 18.
She had wanted to find an opportunity to get a tissue sample from him for research — ideally a brain slice, which might help advance some of her projects.
But between her hospital consultations, research, meetings, and teaching classes at Tracen Academy, she simply hadn't found the chance.
She never expected him to walk right into her hands today.
The reason? Exactly what she had mentioned — he had been sent flying by a horse girl running at several dozen kilometers per hour.
Under normal circumstances, anyone hit like that would suffer internal injuries or broken bones at the very least. Yet Yasui Makoto only had a mild contusion.
According to the horse girl who brought him in, he had even stood up by himself right after the impact and looked completely fine.
This meant his mind wasn't the only thing that was impossibly outstanding — his physical constitution was also unbelievably strong.
Now then… what kind of excuse should I use to get this interesting little guinea pig into a slicing procedure? Hohohoho…
She took another sip of tea, pretending to ponder his condition while her mind raced.
Being stared at by those crimson eyes, Yasui Makoto felt a chill run down his spine for some reason. He had heard rumors about this horse girl — something about her being very enthusiastic about human experimentation.
Although the rumors had never been confirmed, right now he was clearly fine, yet she was deliberately putting on a serious "thinking about the illness" act. There was no way he believed she didn't have some scheme in mind.
He could read the X-ray himself. Not only because becoming a Central trainer required sufficient medical knowledge, but also because in his previous life he had been an "extreme stunt performer."
"Extreme stunts" was a relatively new sport, a type of extreme athletics that combined and elevated high-difficulty moves from various other disciplines — such as gymnastics twists, martial arts flying cross armbars, capoeira's spinning kicks, and more — into even more spectacular and challenging routines.
The danger of the sport went without saying. In his previous life, despite his outstanding talent, he had made a mistake during a high-altitude performance when an aircraft accident occurred, and he had crossed over to this world.
Only then did he discover how peculiar this world was.
There were no horses here. Instead, there were "horse girls" (Uma Musume).
They had long ears and horse tails, were blessed by the three goddesses, possessed physiques far surpassing humans, and were born with extraordinary talent.
Their leg strength in particular was astonishing — their average running speed could reach 60 km/h.
They loved running, which led to the creation of Tracen Academy, an institution dedicated to training horse girls.
In this life, both of his parents were connected to Tracen Academy. His father was a local trainer, and his mother was a retired local horse girl.
He didn't hesitate at all and decided to become a horse girl trainer.
For an "extreme stunt performer," the greatest dream was to challenge the limits of the human body or witness the most extreme performances.
Horse girls looked just like humans but had far superior physical abilities. This perfectly struck at the heart of his dream.
He wanted to see just how far these beings of this world could push their limits.
He also wanted to know whether, by watching their performances, he could break through the limits of humanity.
With that expectation, and relying on the memories and abilities from his two lifetimes, he was accepted into the Trainer Academy right after graduating junior high.
Immediately after graduating from the academy, he passed the exam to become a trainer at Central Tracen Academy and moved to Tokyo a few months ago.
It was normally very difficult for a rookie trainer to sign contracts with horse girls. Most had to shadow a senior trainer for a while before gradually starting to coach independently.
Yasui Makoto, however, felt he didn't need to do that.
His various abilities were not quite at the absolute peak of the industry, but they were easily first-class level.
Combined with the professional trainer knowledge he had already absorbed with his parents' help from a young age, he was confident he could guide horse girls who would be outstanding and dazzling.
Of course, others didn't think the same. In the few months since arriving in Tokyo, he had approached many horse girls, only to be politely rejected every time.
Today he was rejected again. Perhaps a little distracted because of it, while waiting at a red light to cross the road, he saw a child about to be hit by a car. Without thinking, he rushed forward.
He saved the child… and got sent flying himself.
Not by a car — but by a black-haired horse girl.
Fortunately, he had faced similar extreme reaction situations in his previous life. On instinct, he adjusted his posture mid-air and didn't suffer serious injury.
He had wanted to just leave, but the horse girl who hit him was clearly terrified. She kept apologizing nonstop and insisted on taking him to the hospital for a check-up.
After refusing several times and seeing how stubbornly she refused to let it go as if saying "I'll follow you until you agree" he had no choice but to come to the hospital.
He never expected that while being hit by the horse girl had been fine, coming to the hospital would land him in the hands of the eccentric Dr. Agnes Tachyon.
And now she looked like she wanted to dissect him. While feeling a headache coming on, Yasui Makoto secretly began thinking of ways to escape.
At that moment, after staring at him for a long while, Agnes Tachyon finally spoke slowly:
"As for other issues… it's hard to say for now."
"If there are any problems that only show up after a few days, that would be troublesome.
"So, my suggestion is that Yasui-kun should stay here for a while so we can observe you properly.
"Also, you should probably undergo some craniotomy for a more thorough examination…"
Yasui Makoto's scalp went numb. He immediately confirmed that this horse girl really was planning some kind of slicing experiment.
Before he could refuse, there was a loud bang — the door to the neurology examination room was slammed open.
A black-haired horse girl burst in.
The moment she charged in, the door handle made a painful creaking sound, and a large chunk of the door panel was ripped off along with it.
"C-Craniotomy?! I-Is it that serious?!"
Under the surprised gaze of Agnes Tachyon and the stunned look of Yasui Makoto, the black-haired horse girl let out a cry, then unconsciously glanced at the door handle she had just ripped off and at the hole now in the door.
"S-Sorry! I-I was too reckless…"
She quickly hid the door handle behind her back and bowed deeply.
"D-Doctor Agnes Tachyon, hello!
"M-My name is Kitasan Black! I'm a new first-year student at Central Tracen Academy this year! Please take care of me!
"I-I… anyway, I will take full responsibility for everything that happened to Mr. Yasui!"