"If you have any more of those fine filtration cups, he would definitely sell them," Jenny laughed.
Filtration had always been a major headache for her; she had previously used water filter pitchers delivered from the bunker, which were only good enough for filtering out coarse residues. The filters needed to be replaced pretty often.
On the other hand, the filtration cup she just examined, which had a five-layer filter, seemed quite effective.
"Do you mind if I try?" she pulled out a leather water pouch from her belt to compare.
"Of course not," Yu Hong stepped back to let her pour water into the filtration cup.
Soon, clear water streamed out, making Jenny's eyes gleam. Cleaner water was in high demand, for instance, for washing wounds during treatments.
After completing the trade, the two retreated and quickly went their separate ways.
On his way back, Yu Hong found the type of soil Jenny had mentioned, scooped up a lump, and brought it back to the cave.
He intended to try enhancing it; if the soil indeed had antidiarrheal properties, the Black Mark should be able to enhance it into a medicine with fewer side effects.
This was his actual trump card!
If the enhancing process was timed right, he could be looking at another source of revenue through bartering.
Elsewhere.
Jenny hurried through the woods and stopped in front of a grassy area, bent down, and cleared away the weeds to uncover a pull ring.
Grabbing the pull ring, she lifted it upward.
Instantly, a wooden board disguised as grass stood upright.
Underneath the wooden board was a simple tunnel.
She dove in and crawled along the dark tunnel for more than ten meters until reaching its end.
At the end, there was a grayish-black metallic circular door.
Knock, knock, knock.
She knocked on the door, then without waiting for a response, she took out a key, inserted it into the keyhole, and turned it to open the circular door.
Behind the door was a small square room adorned with an atomic lamp, casting a faint green light over everything.
This was her personal bunker, furnished with tables, chairs, cabinets, a bed, and tools—everything necessary, including plenty of leatherworking tools and raw materials.
Jenny emerged from the tunnel, shut the door behind her, stretched, walked over to the cabinet, poured the filtered water from the cup into a small pot, and waited for it to boil.
Then, she walked over to the bookcase, sat down, took out a charcoal pencil and newspaper, and prepared to write about the encounter with Yu Hong today.
"Mom, did you just go out?" Suddenly, a crisp female voice came from another room.
The bunker had a small hall and three rooms; one room was for leatherworking, one was the bedroom, and the other was a storeroom.
The voice was coming from the bedroom.
"Is that you, Aifu? When did you get back?" Jenny turned towards the sound with a delighted expression.
"I just got back a while ago." A girl with a golden ponytail walked out of the bedroom, dressed in a green hoodie and tight jeans, with a delicate face seemingly lightly made up.
She was Jenny's daughter, Aifu, considered the prettiest girl among the local survivors.
"Do we have any food, mom? I just checked, and there was nothing," Aifu said discontentedly.
"There is some left..." Jenny rose quickly, rummaged through a corner, and pulled out a small bag of jerky. She opened the bag, took out half, and was about to hand it to her daughter.
Unexpectedly, Aifu snatched the whole bag in one swift move.
"There's still so much left. Thanks, mom, I knew you're the best," she said cheerily, kissing Jenny quickly before dashing out the entrance.
Jenny's hand hovered in mid-air, even the jerky she held taken away.
She managed a wry smile but did not stop her.
She did not get the chance to say that this was most of her food reserve for the month,
Now that it was all taken, what was left was barely enough for her to subsist on clear broth each day...
Exhaling deeply, Jenny suddenly smiled again.
"So eager to eat, she must be starving... No matter what, as long as I can help her..."
She did not dwell on why her well-doing daughter would suddenly run back from town or why she didn't consider her at all.
All she knew was that since her husband's death, Aifu was the only family she had left.
'She's still young, she'll understand in time...'
Comforting herself, she continued to work on repurposing some old clothes into new fitting garments, another trade she had bartered for.
*
*
*
Click.
The door to the cave was pulled open.
Yu Hong stepped in quickly, embraced by a familiar foul smell that instantly comforted him.
He closed the door and opened a window to air out the space.
He picked up a protein stick, tucked it into his mouth, and chewed slowly. At the same time, he placed the freshly dug-up soil on a sheet of newspaper.
Finally, he pulled up a wooden stool and sat opposite the fireplace, quietly watching a newspaper showing a countdown under "Comprehensive Physical Training Method."
At that moment, the countdown had just over five hours remaining.
Yu Hong decided not to wander off and just sat quietly on the stool, waiting for the time to pass.
One hour...
Two hours...
Three hours...
The sky outside began to darken.
The wind in the woods grew stronger, making louder whistling noises.
Yu Hong stood up, stretched his waist and legs, and pulled over the flap for the peek window.
He also swapped the half-depleted enhanced pyroxene for the only intact enhanced pyroxene he had left.
After carrying out these tasks, he took the cooled pot of water, poured it out, and cautiously sipped some with a cup to prevent dehydration.
'After the rain, a day's sunshine isn't enough to dry the wood; there's no dry firewood. Tonight, I'll just have to make do...'
He calculated the remaining firewood, took out a candle, and placed it where he could easily grab it.
Then, he lay down on the bed, his gaze fixed on the door, waiting for the night to arrive.
Within about twenty minutes...
The sky had completely darkened.
The familiar rustling sound of crawling came once again.
Yu Hong quickly got up and lit a candle with the remaining charcoal in the fireplace.
The candlelight illuminated the entire cave.
Taking advantage of this time, he began to ignite the fireplace.
At night, the temperature outside had dropped to just a few degrees.
As the black bugs swiftly swarmed in, the fireplace, slowly ignited by Yu Hong, began to burn.
Chunks of dry wood were added, and the burning flames lit up the entire cave.
Time also passed continuously in such monotony.
Midway, Yu Hong had diarrhea twice, both times completely dehydrating, making his complexion increasingly pale and his lips more colorless.
Finally,
Under his continuous watch, the enhancement of the Advanced Physical Training Method had ended.
After a blur, the previous newspaper instantly turned into a thin black manual.
The manual was the length of a palm and about as wide as an adult's palm. Its cover was neatly printed with: Advanced Physical Training Method.
Seeing this scene, Yu Hong's eyes lit up; he quickly set aside the dry wood he was holding, walked over, and picked up the booklet.
In the firelight, he eagerly and quickly turned to the first page of the booklet.
Suddenly, a standard running action diagram appeared before him.
The diagram depicted a bald man with no clothes.
However, this man had no skin, clearly displaying all the muscles, tendons, and bones beneath the skin.
The places where force was applied were colored in red, and the directions and intensities of the forces were marked.
Yu Hong glanced at the text above the diagram: Basic Qi Cultivation Technique.
"Isn't this just running?" He carefully checked the details on the diagram, confirming that this thing was indeed an extremely detailed running guide.
But he clearly remembered that during the enhancement, he had intended guides toward the cultivation of martial arts, inner strength, etc.
His thought at the time was, although the name was Advanced Physical Training Method, a slight deviation in direction wouldn't matter.
But this... is it?
Yu Hong's brow furrowed, he sighed, and continued turning the pages with patience.
The content on the second page made him relax his brows a bit.
The second page showed a breathing internal strength diagram to supplement running.
It was the same skinless bald man, and inside his body, red and blue arrows marked the rhythm, quantity, duration, and path of exhalation and inhalation.
Next to it, there were small written instructions suggesting that while running, one should visualize a special pattern.
See page three for the pattern.
Yu Hong flipped to the third page.
It was the visualization pattern.
It looked like a bizarre pattern mixed with black mud and silver sand.
At a glance, Yu Hong felt slightly dizzy, as if his eyes were being sucked into it.
He dared not look further because below it was written in small letters: Do not view before practicing.
He turned the page again.
Last were some herbal ingredients that needed to be taken in conjunction, which Yu Hong inspected carefully, only to find, surprisingly, that these herbs were common in the surrounding forest.
There were also precautions and warnings.
'This exercise method is custom-designed based on personal physical and mental environment and other factors, and is not intended for use by anyone other than the individual. Attempt at your own risk.'
"So intelligent?" Yu Hong felt increasingly in awe of the magic and power of the Black Mark.
Closing the last page, he suddenly realized, could it be that this so-called Advanced Physical Training Method only provided him with a slow jogging exercise diagram?
The rustling black bugs continued to crazily swarm into the doorway.
The noisy sound brought Yu Hong back from his thoughts.
He quickly set down the booklet and hurried to the fireplace to add more wood.
As he added wood, he also carefully recalled the training method he had just read.
'It didn't say you have to run outdoors; it seems that running in place indoors might also work. I'll try it inside the house first.'
Unfortunately, as good as the idea was, after running in place for just two minutes, he felt his legs weaken and lost strength.
Because he hadn't eaten anything, only drinking water and already dehydrated, his body lacked replenishment and entered a state of fatigue.
Thinking of this, Yu Hong quickly came to his senses, remembering he hadn't taken the medicine yet, and his diarrhea hadn't improved.
He immediately stuffed a piece of wood into the fire and walked to the mound of earth he had dug during the day, reaching out to touch the earth.
'Enhance antidiarrheal medicine, direction: reduce side effects,' he muttered in his mind.
If this mound of earth really had natural antidiarrheal properties, then the Black Mark enhancement should be successful.
But if it was ineffective, then the Black Mark might encounter the same issue as before, lacking completeness and unable to enhance.
This would also serve as a way to verify the authenticity of its effectiveness.
Yu Hong stared at the soil, his eyes unblinking, quietly waiting.
Hiss.
Soon, a black line flowed from the Black Mark on the back of his hand, burrowing into the soil.
Then, a familiar countdown appeared on the surface of the soil.
This time, on the already black soil, the countdown was not black, but a striking red.
'1 hour 51 minutes'.
It was real!
Yu Hong's eyes brightened, and a look of relief washed over his face.
Although he felt that Jenny had no reason to deceive him, seeing the result truly eased his mind.
In this dangerous environment lacking medicine, being able to reliably produce enough antidiarrheal medicine would be a great thing for him and for others.
'Enhance antidiarrheal medicine?' came the cold mechanical voice of the Black Mark.
Yu Hong licked his cracked lips.
'Yes!'