The final test was complete.

The former Battalion Commander… no, Test Subject #1 was able to drink water healthily.

Aside from the water tasting of limestone, there were no side effects.

Additionally, His Imperial Highness Eun sent a few more men, and the results were the same.

Indeed, I am amazing. Heh!

Jin Cheonhee himself also tried it directly, and the performance was certain.

Woof!

“Hey… don’t criticize me too much. Testing it myself is the most accurate way.”

Squeak!

“See? It was fine, wasn’t it?”

Hwanggu and Noe-jin each scolded Jin Cheonhee in their own language, and Jin Cheonhee understood exactly what they were saying even without a translation device.

“But I can’t sell something I haven’t tried myself.”

Neither could argue with that point, so they were briefly speechless before eventually tugging on both sides of Jin Cheonhee’s robe.

“Alright, alright. You mean I should make it even safer, right?”

Peep! Growl!

Each made their own comment.

Jin Cheonhee gently patted their heads and nodded.

But what more could be done to make it safer?

Originally, Jin Cheonhee had planned to test it on himself first, but His Imperial Highness Eun stopped him and instead sent Test Subjects #1, #2, and #3—criminals and corrupt officials.

Though safety had been thoroughly verified, it seemed best to conduct the final test personally.

From Jin Cheonhee’s perspective, it was fastest to examine his own body’s pulse.

After successfully completing the final experiment, His Imperial Highness Eun and the Third Prince summoned Jin Cheonhee.

The Third Prince spoke, “If it’s acceptable to you, I’d like to sell your product. It could save many merchants and nomads crossing the desert.”

At those words, one of His Imperial Highness Eun’s eyebrows bent uncomfortably.

“I wonder if you’re forgetting something. Raman, this person is my guest.”

“But isn’t there no particular order for initiating trade? As someone who also operates a caravan, I must have that tube.”

Sparks flew between the two.

Wow, the Third Prince has quite a temperament too.

Was it because of his bright and gentle impression?

Or because he seemed like a K-idol type who enjoyed playing instruments and cooking?

Despite His Imperial Highness Eun’s discomfort, he didn’t back down.

His Imperial Highness Eun also showed no signs of yielding, seemingly concerned that what was his might slip away.

“I don’t mind. I’ll give it to both of you. Just give me ten percent of the sales profit as… um… intellectual property fee.”

If martial artists fought with swords, what would happen if two central powers fought? That would be war.

His Imperial Highness Eun asked, “Ten percent? I believe thirty percent is the usual rate…”

Ahaha, it seems you’ve already investigated the ondol heating systems.

The royal blood of the Hua Empire leaves no gaps.

Well, it’s best to speak properly.

Jin Cheonhee straightened his back and adjusted his posture. Then he looked directly at the two men.

Not at them as caravan leaders, but at an Emperor and a Prince.

“This item is directly connected to lives. Lowering the unit cost is more important than making a profit. Also, we shouldn’t allow fakes to circulate.”

“Why do you think so?”

Jin Cheonhee scratched his cheek.

“If counterfeits are made, they’d have to be cheaper than the real ones, which means performance would certainly be greatly reduced. Then people will die. It’s different from Go or ondol heating systems.”

People don’t die just because they don’t play with Go, and ondol can be replaced with other heating devices of this era.

But with this item, people die.

Jin Cheonhee knew how murders occurred in Africa.

People kill others for too many reasons.

The Life Straw had enough functionality and price to potentially kill others.

Still, the Central Plains are different from Africa. Ironically.

Jin Cheonhee doesn’t know why modern Africa is more hellish than the Central Plains of this era.

No, there are many reasons if he were to explain.

Exploitation since the Age of Exploration, plantations, the creaking territorial administration since liberation… advanced countries selling weapons to the military, creating civil wars, continuing abnormal weather.

Environmental pollution pushing from the poor lower strata.

Polio, malaria, and AIDS killing children, education becoming increasingly difficult.

However, he doesn’t know for certain which one of these has a definite solution.

He’s just a surgeon, not a politician.

Fortunately. And strangely.

Why is the medieval Central Plains better than the modern era?

Perhaps human poverty isn’t due to the absence of science, but just someone’s ignorant greed.

“At this price, even low-ranking caravan guards can afford it with their monthly salary. I set it at roughly the cost of three meals at an inn. That’s a price people would be willing to pay to try it out.”

“Isn’t that too cheap?”

“If more profit is made, counterfeits will certainly circulate.”

“…”

The Third Prince fell into thought.

His Imperial Highness Eun probably didn’t think much of it since he would supply it to soldiers and officials anyway.

But the Third Prince was in a different position.

He was not a king.

Having given up his right to succession early on, he now ran a caravan.

This clearly wasn’t a very profitable business.

Moreover, he was facing an impending major surgery.

He must have considered what life would be like after the surgery.

The young man stared at the small tube in Jin Cheonhee’s hand.

The eyes of a merchant, discerning value and calculating price.

What did his eyes see?

Finally, his lips parted.

“May I ask for one more thing?”

“What is it?”

“I want to improve the kingdom’s wells. Could you lend me your wisdom?”

It was about endemic diseases.

Though not as bad as the oases, these parasites were spreading quietly throughout Wannong.

He hesitated before speaking.

“You may have already noticed, but I am a prince of a kingdom. I think this is cheap for the price of a life, but I don’t want to contract such a disease again.”

Suddenly, Jin Cheonhee thought this person might make a good king.

But he ended up shaking his head.

Instead, he said with the brightest expression possible:

“Of course. I’ve always been concerned about improving water sources. However… it will cost quite a bit.”

“Whatever it takes!”

The Third Prince nodded with a bright voice.

Suddenly feeling a tingle on the back of his head, Jin Cheonhee turned around to see His Imperial Highness Eun grinning.

“I’d like to hear about that too. Could you tell me? Preferably drawn as design plans.”

That smile. He had seen it recently.

Ah… he’s considering kidnapping me.

Had he gotten too deeply involved?

But isn’t it unavoidable! These endemic diseases must be eradicated as much as possible!

So that physicians… no, healers can have an easier time!

‘I should take care of myself for a while, so I don’t get caught by the netbag grandfather[1]… No, by the netbag Imperial Highness Eun.’

***

One week later.

Finally, the physicians and equipment from the White Dragon Medical Pavilion’s branch arrived.

Although the branch physicians were seeing Jin Cheonhee for the first time, they immediately recognized him from the giant yellow dog, the Heavenly Noe-jin, and his legendary good looks.

“We were delayed due to bandits, Junior Pavilion Master. Here, the branch physicians greet you.”

All the physicians paid their respects to Jin Cheonhee.

Jin Cheonhee returned their greetings with a cupped-hand salute.

“That’s alright. More importantly, I’m relieved that no one was hurt and nothing was damaged.”

At those words, the most senior physician shook his head as if to say “don’t even mention it.”

“The swordsmanship of the escort warriors was like lightning—too fast to be seen. To think there could be so many peerless experts in one caravan… I can only think that the world beyond is truly vast…”

“Ah, hahaha…”

Jin Cheonhee glanced at His Imperial Highness Eun while sweating nervously.

His Imperial Highness Eun answered nonchalantly:

“Not at all. I simply spared no expense to save an old friend.”

“Ah, so that’s why you hired such excellent warriors.”

“Yes. And calling them peerless experts is an exaggeration.”

“My eyes are dim, so I don’t really understand the realm of warriors. I’m just grateful for the safe journey.”

I could bet my morning egg toast that there were imperial guards mixed among them.

Of course, it was toast made with the local wheat bread since modern white bread wasn’t available.

Dip in egg wash, sprinkle with sugar, fry it, then layer it with fruit sauce, chopped cabbage, onions, ham, cheese, and so on…

Just thinking about it makes my mouth water.

Why are all fattening things so delicious?

His Imperial Highness Eun, by the way, devoured three different kinds.

I’m starting to worry that I might end up being kidnapped not as an imperial physician or technical advisor, but as an imperial chef.

Sigh, tonight I should make plain spicy chicken stew to avoid being kidnapped. With lots of potatoes thrown in.

And I must finish by frying rice for the grand finale.

Even if I try to keep it simple and ordinary, as long as K-Korean blood flows in Jin Cheonhee’s veins, mixing rice is inevitable.

I wonder if he’ll eat three bowls of this too.

I don’t know if he’s naturally a big eater or if he just enjoys my cooking, but His Imperial Highness Eun has been consuming my dishes enormously.

“Junior Pavilion Master. We await your instructions.”

Jin Cheonhee nodded.

It was time to open the White Dragon Medical Pavilion temporary branch surgery clinic.

***

With all staff gathered, it was now time for meetings, practice, and patient condition management.

Jin Cheonhee continuously checked the Third Prince’s condition by examining his pulse.

He did so again on the morning of the surgery.

“Hmm… you’re surprisingly relaxed for someone about to have their abdomen opened.”

At Jin Cheonhee’s words, the Third Prince smiled slightly.

“It’s not like you’re cutting open my belly to kill me—you’re saving me. What’s there to be afraid of?”

Hmm, this person also shows signs of having lived a tough life.

I knew he hadn’t lived a pampered life, but…

It’s a different feeling from the threat to life when encountering bandits while conducting business.

Perhaps he didn’t become a merchant because he wanted to.

But that too was a choice.

Best to pretend not to notice.

The Third Prince said:

“You’re not nervous either, physician.”

“Being nervous ruins the work.”

When Jin Cheonhee grinned somewhat shamelessly, the Third Prince grumbled quietly:

“You can smile like that because you have skill, right?”

“Of course. Let’s finish quickly and eat something delicious together.”

Since the Third Prince was staying in the mansion guestroom, he naturally ended up eating the dishes Jin Cheonhee prepared.

Surprisingly resistant to spicy food, he became invincible once cheese was added.

“It’s strange. We’ve only known each other for a month, but it feels like we’ve known each other for a long time.”

“Typically, it’s human psychology to grow attached to someone who feeds you. It’s an animal instinct.”

“Ah… so that’s why.”

“Is there anything you’d like to eat? Of course, you can’t eat it right after surgery. After you recover.”

At Jin Cheonhee’s question, the Third Prince pondered deeply before answering:

“Um… that pork simmered in sweet and savory sauce.”

He means braised pork ribs.

I’ve never met anyone who disliked it.

Children, adults, even people who say they dislike pork—everyone falls head over heels when they eat this over rice.

“That’s perfect for celebration.”

Jin Cheonhee said this and released the Third Prince’s wrist.

“Well then, let’s begin the surgery.”