Tachyon's black market was set inside one of the Academy's laboratories.

At exactly 01:10, the pitch-dark room suddenly lit with pale violet light. The shut door slid open on its own, revealing the scene within:

The lab's layout was similar to a normal classroom's, but details here and there had been altered, clearly refitted by someone in secret.

The blackboard was scrawled full of complicated chemical formulas. At the very center, the largest characters of all: [U=ma²].

The ceiling lights stayed off. Instead, the walls were smeared with some kind of phosphorescent powder, glowing faintly violet. Ranks of flasks and beakers filled with multicolored solutions were neatly arrayed across the tables, each tagged with a warning: [DO NOT TOUCH].

In the center, the original rectangular podium had been remodeled into a bar-like circle. To the left and right stood skeleton models—one human, one Uma. Their bony hands clutched a test tube and a dropper, as though they were guardians of this place.

And on that podium sat an Uma with messy brown short hair, sleeves of her white coat trailing absurdly long. One leg crossed over the other, she leaned her cheek on her hand, and with those red eyes—etched with blinds-like stripes—she scanned the doorway, regarding the arriving customers like guinea pigs in a cage.

"Welcome~"

Agnes Tachyon. The mad scientist of Tracen Academy.

She rarely appeared in public. Almost all her time was spent shut in the Academy's laboratory provided to her, immersed in her experiments. Only when a scheduled race approached, or final exams, would she show her face at all.

Yet even if she seldom appeared, her reputation in Tracen was massive. The reason: the potions she developed had provided enormous "help" to many Uma who wanted to advance their relationships with Trainers.

Statistics—unofficial—told the story. Before Tachyon's drugs circulated, the graduation marriage rate between Uma and Trainers was only 40%. As long as Trainers kept their distance and asked the school for help at critical moments, their chastity could still be guarded fairly easily.

But after her drugs entered the market? The marriage rate skyrocketed! Now—90%!

And the other 10%? Only because some Uma shared the same Trainer, and by Japanese law multiple Uma couldn't legally marry one man. In those cases, one would be chosen to walk the ceremony first, the others joining in afterward.

Whether the Trainer agreed or not—once a bottle went down his throat, there was nothing left but the Uma Dance of joy…

Thus, Tachyon was both angel in Uma's eyes—

And demon in Trainers'.

And this enemy of Trainers now calmly introduced tonight's wares to the crowd of Uma at her door.

"[Sleeping Red Tea]—smells and tastes exactly like ordinary black tea, but once a Trainer drinks, he'll fall into steady sleep. No matter what's done to him, he won't wake."

"[Stamina Drink 2.0]—boosts a Trainer's stamina. Stronger than version one. He can go three days and nights without tiring. Side effect: when it ends, he'll sleep three days and nights."

"[Pelvic Durability Enhancer]—as the name says. Increases pelvic resilience. Longer lasting."

"[Tachyon Cola]—drink it, and a certain place will glow."

"[Want-a-Hug Potion]—comes in A and B bottles. The one who drinks A will desperately want to hug the one who drank B. Remember: you take B, Trainer drinks A."

"There are many more for sale tonight—[Scent Eraser], [Presence Reducer], and so on. But I doubt you care much, so no need to list them all."

Tachyon hopped down from the podium, settled in a chair, then bent to haul box after box of cartons up onto the counter.

She patted her sleeve-covered hands together, smiled toward the door.

"Quantities are limited. First come, first served."

"!"

The moment she said it, the Uma who had been cautiously peering in couldn't hold back. They surged forward into the lab.

They shoved, scrambled, all trying to seize the front row so they could grab their desired potion first.

One lone weak human, lacking any chance in this fight, could only watch as the Uma pushed past, and slowly shuffled himself to the very back.

After a brief scuffle, one particularly strong Uma fought through, reaching Tachyon first, panting heavily.

"Tachyon-senpai, I want ten bottles of [Stamina Drink 2.0]. How much?"

"[Stamina Drink 2.0], hm…" Tachyon thought, pulled out a bottle of blue liquid from the box, and swirled it lazily.

"One bottle, five hundred thousand yen. Ten bottles—five million~"

"How much?!"

From the very back, Mizuno's head shot up. He stared wide-eyed at the tiny 100ml bottle in her hand.

This stuff—500,000 yen for one?!

He fumbled through his own "savings pouch." The numbers chilled him: he couldn't even afford one bottle.

He still had about 400,000 yen left—even after buying special parts from Hayakawa-san's friend, even after funding Urara's victory party. He'd been confident he had enough left to buy a bottle of each potion tonight, to take home and research their strange effects.

But now? He wouldn't even be able to afford the one potion he needed—much less spare any for experiments.

For the first time since coming to this world, Mizuno truly felt the bite of poverty.

Especially when that Uma at the counter casually forked over the cash—five million yen, just like that—and bought her ten bottles without blinking. Mizuno felt his own wallet shrivel to nothing.

"What now…" He was trapped.

He'd never imagined Tachyon's potions would be this expensive. Oh, the effects justified it, sure. But he was just a low-salary Trainer. His entire purse relied on Mejiro McQueen slipping him "tips" in exchange for Honey Drinks.

And it was one in the morning. No one to borrow from.

If he missed this chance, who knew when the next black market would open. And the Empress—she couldn't wait that long.

Only one option remained…

"Hhh—" Mizuno sucked in a breath, staring at Tachyon gleefully raking in money at the counter.

Would he have to sell his own labor… to buy a potion?