The sun set at dusk.

Chu Mu clutched a set of clothes. At his courtyard gate, the young widow, with a hint of shyness, turned and left. Her graceful figure was all that remained before she quickly vanished from sight.

’Interesting...’

Chu Mu chuckled. The young widow’s sudden gesture of thanks had been rather unexpected.

He spread out the Qingyi robes in his hands. A single glance was all it took for Chu Mu to see that they would fit him perfectly.

’This young widow... she really is interesting.’

It was only a moment ago that he had learned the young widow’s full name: Li Caiyi. She was merely sixteen years old.

In a more modern time, she would still be a naive young girl, but in this world, she had already endured far too much.

After standing in the courtyard for a moment, he folded the clothes. He stared at them for another moment before shaking his head, turning, and walking into his room.

The unfinished brainstorming session resumed. With each new experiment, the lingering aroma of herbs in the room grew ever thicker.

It wasn’t until twilight deepened that Xu Yuan’s arrival finally broke Chu Mu’s concentration.

"Brother Mu, what are you doing?"

Xu Yuan looked around the room, clearly confused.

"You’ll see in a bit."

Chu Mu shoveled the food Xu Yuan brought into his mouth, mumbling indistinctly.

Then, as if he thought of something, Chu Mu looked up at Xu Yuan and changed the subject:

"Right, for the next little while when you’re on patrol, keep an eye on the young widow next door for me. If there’s any trouble, take care of it."

Xu Yuan’s eyes went wide, as if he’d just heard some earth-shattering secret. "Brother Mu, you and that young widow..."

"Get out of here!"

Chu Mu snapped, "What are you thinking? During the riots, I saved the young widow. Today, she came over to thank me and even gave me a set of clothes."

"Since we have this connection now, I can’t just sit by and do nothing if she runs into problems..."

Xu Yuan, looking like he understood everything perfectly, immediately pounded his chest and declared, "I get it, I get it! Don’t you worry, Brother Mu. As long as I’m around, you can rest easy. If anyone dares harass her, I’ll break their legs..."

Seeing his reaction, Chu Mu didn’t even bother trying to explain. The more he’d try, the murkier it would get, and it would only make him look like he was hiding something.

After finishing his meal, Chu Mu got up and walked straight to the medicine cabinet. With the Centimeter Scale back in his hand, he began the experiment for the sixteenth revision of the Essence Qi Powder.

About half an hour later, a scalding medicinal decoction was once again on the table.

This time, however, there were two porcelain bowls on the table instead of one, and both were filled with the decoction.

"Here, one bowl each. Don’t let it go to waste!"

Chu Mu picked up a porcelain bowl and handed it to Xu Yuan.

Xu Yuan was puzzled. "Brother Mu... what is this?"

"It’s an improved version of Essence Qi Powder. This is the sixteenth revision, so it should be fine. You try some, feel how the medicinal properties affect you, and then tell me what happens..."

With that, Chu Mu downed the scalding decoction. Seeing this, Xu Yuan didn’t hesitate either, drinking his own bowl in one go. Noticing Chu Mu had closed his eyes to sense the effects, Xu Yuan followed suit, closing his eyes to sense his own Qi Blood.

Nearly fifteen minutes later, Chu Mu slowly opened his eyes. The Spiritual Radiance Blessing gradually faded, and the profound look in his eyes gave way to a hint of confusion.

He walked to the table, picked up a brush and dipped it in ink, but Chu Mu hesitated to put it to paper.

"Brother Mu, the medicinal effect is so strong! It’s probably more than twice as strong as my Essence Qi Powder!"

Xu Yuan was obviously very excited, and even a little incredulous.

Chu Mu said, "Tell me what you felt just now."

Xu Yuan recalled, "Well, the effect was really strong. But... my heart felt a little uncomfortable. The rest was fine..."

Chu Mu fell into thought. After a long moment, his brush finally touched the paper.

Essence Qi Powder, Revision 18: a slight increase in efficacy compared to Revision 17. Approximately double the efficacy of the original Essence Qi Powder...

The toxin load problem remains unresolved. Long-term use may lead to excessive heart strain, endangering one’s life...

For normal use, it must be taken only once every ten days, and requires a corresponding antidote for the toxins...

He wrote line after line. Finally, the brush stilled, and Chu Mu frowned in deep thought.

From the first revision to the current eighteenth, the massive leap in the Essence Qi Powder’s efficacy was primarily due to the complementary balance of orthodox and unorthodox components in the formula.

The so-called unorthodox referred to poison, and a potent one at that!

The potent poison, when neutralized by the specific combination of primary and supplementary herbs in the formula, had its toxicity partially eliminated. Moreover, this very poison was used to greatly enhance the effects of the primary ingredients—it was a sublimation of their power!

But an equally unavoidable problem was the existence of residual toxins.

To make use of the poison, its potency couldn’t be weakened through pre-processing. The only way was to let it take effect and then attempt to neutralize and weaken it within the confines of the formula itself.

’Made by poison, broken by poison!’

The current eighteenth revision of Essence Qi Powder seemed to have fallen into this vicious cycle.

No matter how effective the medicine, if the side effects were this severe, the formula was meaningless.

’What I want from an Essence Qi Powder formula... the most important factor isn’t potency, but time.’

The original Essence Qi Powder formula, for example, had mediocre effects and still required a waiting period of several days between doses. That time restriction alone made it impractical.

If he couldn’t solve the problem with his current formula, the ten-day interval and the need for an antidote made it even more so!

’Change the supplementary herbs... or maybe... when taken to an extreme, things will reverse?’

Chu Mu’s brow was furrowed in thought for a long time. Then, his stalled brush moved again. As he thought, the formula for the nineteenth revision slowly materialized on the paper.

As the night deepened, Chu Mu remained busy in his room. Xu Yuan, who had been summoned, had become Chu Mu’s other human test subject.

Revision after revision of the formula was tested on both Chu Mu and Xu Yuan.

The experiments only ceased late into the night. Chu Mu fell asleep in his clothes, while Xu Yuan went to spend the night in the guest room next door.

For the next ten-odd days, Chu Mu’s life continued in this orderly yet obsessive fashion.

He experimented day and night, revising the Essence Qi Powder formula again and again. Sometimes, after several experimental revisions, he would scrap the entire line of thought and start over from scratch, losing count of how many times he’d done so.

Xu Yuan was now a free human test subject, arriving at Chu Mu’s house right on time after his shift every day... to test medicine!

Chu Mu did not go ask for help from Elder Li.

He knew full well that a problem he could rack his brain over for days without an answer could probably be solved with a single sentence from Elder Li.

But after several months of hard study and accumulating a vast amount of knowledge, Chu Mu still hoped to solve the problem completely on his own.

With each experiment, the visible progress on the Light Curtain Panel for the Essence Qi Powder seemed to prove that his independent thought and experimentation were on the right track.

The experimental process of combining theory with practice was, for him, a process of his own growth.

Asking for help from Elder Li would only make this growth of his less than perfect.

This might seem obsessive, but Chu Mu was resolute...

...