His first act was to inoculate the physicians who had already been exposed to the plague.

Jin Cheon-hee did not merely command; he led. He stepped forward and administered the cowpox to himself first, demonstrating the process to the assembly.

I have been saving myself for this very moment.

Seeing the Young Pavilion Master accept the inoculation without hesitation steeled the resolve of the others. It was possible because they were men and women of medicine; they understood the logic, even if the fear remained.

“Well, even if it goes wrong, we’ll just end up with a bit of cowpox, right?” one joked nervously.

Smallpox was a scourge that left no dignity in its wake. Survival was often a curse in itself; those who lived bore the lasting stigma of hundreds of hideous pockmarks, their faces ruined maps of their suffering. Society shunned them. They struggled to find work, and worse, they were often stoned by neighbors who believed that mere proximity to a survivor would invite the pestilence.

So, it begins now.

The priority was to save the living and staunch the spread. Tracing the origin was a futile exercise in an era where the disease was already endemic, but he could at least enforce quarantines and ensure that the dead were cremated rather than buried to sever the chains of infection.

Alright, let’s do this.

No matter the cost, lives had to be saved. Yet, as he prepared, a shadow of anxiety washed over him. Would the people accept this foreign salvation?

***

“We’ve come because we heard that contracting cowpox truly prevents the pox.”

The answer came the very next day. The destitute, those with the least to lose living in the slums, were the first to arrive.

“Yes. That is correct.”

“Is it… safer than variolation?”

Variolation had been introduced in Korea’s history as a method to prevent smallpox, but its volatility had always been its undoing. It was the same here.

“Yes. Side effects occur in perhaps one in a thousand cases… You might suffer from a high fever, but it rarely claims lives.”

How did he know that? Through what rigorous process did he discover it? If such questions were asked…

I can’t answer. I know that.

The biological fact—that those who contracted cowpox developed immunity to smallpox—was a constant law of nature, valid here as it was in his original world. In modern times, it was common knowledge, as obvious as water flowing downhill. But here, it was knowledge that had yet to bloom.

Still, he could not simply let them die for the sake of caution. Unconsciously, Jin Cheon-hee clenched and unclenched his hands, his nervousness betraying his calm facade.

Just then, a voice cut through the tension.

“May I receive it first?”

“Pardon?”

“Since the Divine Physician says he knows a way to prevent smallpox for a lifetime, we should follow it.” The man turned to the crowd. “Right! He’ll drive away the evil spirits with his Mystic Golden Needles!”

…As expected, folk beliefs were inextricably mixed in.

I guess it’s more convincing to believe that illness is driven away by Mystic Golden Needles imbued with internal energy rather than prevented by the cold mechanics of science.

Jin Cheon-hee spoke up clearly.

“Anyone who contracts cowpox will develop immunity. You don’t necessarily have to receive it from me.”

“I see. But anyway, you’re saying you’ll make sure we don’t get smallpox, right?”

Hmm, well, all’s well that ends well?

Living in this era, he had realized that the people here were not stupider than those in modern times. Often, their memory and practical application seemed superior. The only chasm between the modern era and this one was the accumulation of scientific discovery. The modern world stood on a mountain of accumulated data; this era was still laying the foundation stones.

For public education to reach a point where he could explain the mechanism of vaccines, it would take generations. It was just that.

“Still, thank you for coming.”

“We are the ones who are grateful.”

Perhaps he had underestimated the ripples of his past good deeds. Perhaps he had undervalued the weight his name carried in Hangzhou.

Jin Cheon-hee inoculated everyone.

***

After inoculation, the danger was not over. Caring for a child already ravaged by smallpox remained a lethal task until immunity fully developed in the caregivers. However, if a Medical Pavilion refused to care for a sick child, it was no different from gross negligence.

He worried deeply about staffing, but the problem resolved itself with surprising ease.

“Ah, I’ve had cowpox before!”

A Junior Physician from the Hundredfold Benevolence Foundation raised her hand.

She explained brightly, “In my village, the women drove the cows and the men plowed the fields. So, I caught it from the livestock. Thinking about it now, it’s a relief.”

The Hundredfold Benevolence Foundation gathered children from diverse backgrounds and regions. He recalled that he had never discriminated based on origin; only qualification mattered. He hadn’t expected the grace he bestowed in the past to return to him in such a tangible way.

“Everyone is reluctant to nurse smallpox patients. Will you be alright?”

At Jin Cheon-hee’s question, the Junior Physician chuckled.

“If I nurse the patient day and night and still don’t catch smallpox, that proves the Young Pavilion Master’s claim is correct, right?”

“Yes!”

“It is actually fascinating. Maybe because our village raised a lot of cows, there were many people who had cowpox, and perhaps because of that, almost no one caught smallpox. Especially the village women; they were always healthy.”

The Junior Physician pondered for a moment before her eyes sharpened with pragmatic ambition.

“If I remain healthy until the end of this, you’ll include my name in the medical treatise you write later, right?”

Even in a crisis, she ensured her transaction was solid. Jin Cheon-hee’s chest swelled with pride.

She grew up well. So well. Aigoo… my kid.

Doing good deeds was virtuous, but if there was profit to be had, one should take it. He liked her smartness. It was the heart of a professor looking at a well-raised grad student.

“Of course. Thank you.”

“Great.”

Wow, I’m saved.

Jin Cheon-hee sighed in genuine relief.

***

While the Junior Physician cared for the child, the injection marks and the characteristic rash of cowpox bloomed on Jin Cheon-hee’s arm. As soon as his immunity developed, he sought out the Junior Physician.

She looked the same as always.

“I’ve been taking my pulse daily, and as expected, I’m fine.”

“That’s a relief.”

“Just in case, I even tried injecting the smallpox pus from the patient into myself…”

“Hu-huk!”

Jin Cheon-hee waved his arms in sheer panic. Flames of determination lit up in the Junior Physician’s eyes.

“Wait a moment. Young Pavilion Master. I need to rise to become a Senior Physician.”

“No, if you were going to do something that reckless, you should have at least told me!”

“But I really felt like I wouldn’t catch it.”

“Aren’t you trusting me too much?”

At those words, the Junior Physician chuckled softly.

“I have my own experiences from the village. And… Hye… she trusts you.”

Hearing that, Jin Cheon-hee involuntarily looked toward where Sama Hye was working. Since she received the inoculation on the same day as Jin Cheon-hee, she must have developed the rash marks as well.

The Junior Physician continued, her voice softening.

“Of course, there are those raised in physician families to become physicians, but people like me—orphans and strays who became physicians after entering the Hundredfold Benevolence Foundation—we have special feelings for the Young Pavilion Master.”

The trajectory of life for the children of poor martial artists, or those who lost their parents, was usually written in stone. They rolled in the mud, learned the cruel law of the fittest, and eventually climbed the ladder by killing someone. Some headed for the Orthodox Path, but more drifted to the Unorthodox Path. That was due to the brutal cost-effectiveness of evil that Jin Cheon-hee himself had observed in the past.

The Young Pavilion Master broke that cycle for us.

Yet this handsome man, with a sly but gentle face, was looking at her and joking, “Ooh, did you fall for me?” He was cracking jokes just like he did with Squad Leader Man Seon. “And I replied with ‘Well, let’s say I fell for your character’.”

“Hehehe.”

Of course, she hadn’t fallen for him as a man. Honestly, both his face and character were impeccable, but becoming his spouse clearly opened the gates to a chaotic hell.

Still.

Even if it wasn’t romantic affection, reverence for a benefactor was allowed, wasn’t it?

The Junior Physician said firmly, “We, the physicians of the Hundredfold Benevolence Foundation, will always be by the Young Pavilion Master’s side.”

“What about the monthly salary…”

“Of course, assuming you maintain it at the current level.”

The Junior Physician spoke pragmatically, her thoughts drifting to Sama Hye. Sama Hye shared a room with her. The Young Pavilion Master probably didn’t know how much that girl talked about her Benefactor in the quiet of the night.

Rather, he nodded in approval.

“That is a good mindset. People work because there is money. You must survive with that spirit. Still, please tell me first next time. It could have been dangerous.”

Jin Cheon-hee scolded her gently. Then, as if remembering something else, he added one more thing.

“Actually, I should be giving you demerit points for this recklessness. You know that? But… yes. Since I’ve heard such kind words, it’s hard to scold you.”

He smiled bitterly, then his expression shifted to professional seriousness.

“And your wrist.”

“Yes.”

He meant to check her pulse.

Jin Cheon-hee took the Junior Physician’s wrist, his fingers pressing gently against her radial artery for a long time to check her condition. The Junior Physician watched Jin Cheon-hee, whose eyes were closed in concentration.

As expected, he is truly handsome.

Why did poisonous mushrooms look so pretty?

The reason why people, regardless of gender, fell for the Young Pavilion Master was probably just that. Knowing my insides would rot and die if I truly fell for him, this man nonchalantly continued his work, oblivious to his own lethality.

Eventually, his large, long eyelashes fluttered open.

“That’s a relief. You are healthy. Still, just in case, get your pulse checked by me every day. And the treatise… no… let’s put our names together in the medical book.”

“Yes!”

Jin Cheon-hee smiled brightly.

“You must stay healthy.”

At that moment, the Junior Physician’s heart skipped a beat.

Thump—

Damn it.

In the end, she had eaten the poisonous mushroom.

This was a disaster.

***

Leaving behind the Junior Physician who had just stumbled into a doomed first love, Jin Cheon-hee began his rounds.

First, caring for the patients infected with smallpox.

Adults began to flood in, but as expected, children and the elderly were the most numerous.

Why are there always so many children and elderly in hospitals?

He knew the answer in his head. It was because their immunity was weak. Listening to his parents talk about his own childhood, they said he was in and out of the hospital like it was a second home. When an adult was startled, they drank a glass of water and recovered; a child would have a seizure.

But it was the same for the elderly. Many came in after collapsing with a gasp from mere stress.

Was that why? Young martial artists mostly came for emergency trauma from sparring, while the very young and the very old came for diseases like this.

If anything, the elderly… the elderly prepare their hearts. They reflected on their lives, spent time saying farewell to family and friends. They had accumulated a lifetime of memories, and they had sufficient time to prepare their souls for the crossing.

But children were different.

Children couldn’t understand why they were in pain. They only knew fear and suffering, and their parents gouged their own hearts out every time their child cried. The medical staff watching this also tried not to be infected by the suffocating sadness, but enduring it was a trial of the spirit.

It was the same in this world.

The child’s body was covered in blisters. Jin Cheon-hee infused internal energy into the small, trembling frame and continued nursing. It was the same helplessness he felt with cholera. Since there was no proper medicine, symptomatic treatment was everything.

With all a physician’s power, he couldn’t stop more blisters from rising on the child’s skin, nor could he magically end this pain. Keeping the breath attached to the body until the child overcame it on their own was all he could do.

Truly… seeing this makes medicine feel futile.

There were still too many diseases in the world that couldn’t be beaten.