"Sigh… there's just no helping it. Master and Mistress are at it again, flaunting their love like kids despite being hundreds of thousands of years old."
Alone, Dugu Bo sighed as he hugged a thick volume titled Introduction to Human Immunology under the lamplight, silently closing the window.
He was already getting used to it. On the surface, his master and mistress had a predator-prey relationship, but in reality, it was nothing of the sort. Chances were, even they didn't realize how thick the air around them reeked of love—it was almost nauseatingly sweet.
Unaware of his disciple's complaints, Cheng Ying was still rather satisfied with his student. In just a few days, Dugu Bo had picked up most of the biological foundations, and had even memorized all the elements and their properties from the periodic table. He was, without exaggeration, a top-tier student—and seeing his eagerness for hands-on practice, Cheng Ying even thought he had a bit of that Orochimaru-like potential.
After handing the flintlock rifle to Bing Di and personally teaching her how to shoot, she unexpectedly took a liking to the activity and started clinging to Cheng Ying, acting spoiled.
"That repeating rifle you mentioned—the one that's more accurate and can fire continuously—where is it? Hurry up and make it already!"
"Uh… I'd love to! But I can't. Even the one in your hands was made by having a blacksmith forge each part one by one, then I personally ground and assembled them myself. Mass production is impossible. As for more advanced firearms… that's much harder.
"You see, what allows a musket to shoot a bullet is the gas produced by igniting gunpowder. Under high pressure, it propels the bullet forward. But if the threading and locking precision of the barrel isn't high enough, that high-temperature gas will escape from the seams—at best blinding the shooter, and at worst causing the gun to explode.
"To create breech-loading or repeating firearms, we need far greater precision in machining—something I absolutely can't do alone." Cheng Ying shrugged helplessly.
"Lame! And you were bragging about having a weapon powerful enough to destroy empires!" Bing Di pouted and rubbed her chin against his shoulder in protest.
"Eventually, it'll happen. I've already hired people to search for all kinds of minerals. Once we find uranium ore, the brilliance of the sun won't be far off." Cheng Ying lifted Bing Di into his arms, gently tapping her nose with a finger. "We've got all the time in the world—no need to rush. Let's start by making life more comfortable.
"Just recently, I managed to make something that removes the astringency from fruit wine. Come, let me show you what fruit wine tastes like without the bitterness!"
Bing Di didn't think much of it—she just assumed it was another fun little invention like hotpot. Her mouth watered as she followed after him.
But Cheng Ying knew how important this by-product of rendering lard into soap truly was.
Glycerin—a key ingredient in unstable high explosives, an effective treatment for heart conditions, and something that could turn cheap fruit wine into a beverage better than high-end ale.
It would become one of Cheng Ying's signature products…
In the second half of the night, Bing Di—who had treated the fruit wine like juice—ended up collapsing on the table, drunk and dazed. Cheng Ying carried the completely wasted Bing Di back to the bedroom and sighed.
"Four hundred thousand years… and still this body type. I really can't bring myself to lay a hand on her…" Sure, lolis were cute—but few truly had the heart to cross the line.
…
The days that followed were peaceful but full of small surprises. Sometimes it was a new culinary invention by Cheng Ying, and sometimes it was one of Dugu Bo's snakes stealing frogs again.
When Cheng Ying taught Dugu Bo how to dissect a frog, the guy showed zero resistance—further convincing Cheng Ying that he had what it took to become an Orochimaru-type.
As kerosene lamps became more popular, a steady stream of customers came looking to buy or wholesale kerosene, and the little shop began booming.
Bing Di still liked rolling around in piles of gold coins, which forced Cheng Ying to wash all the money—literally. He had to rinse it clean with water.
Later, a particularly imaginative cook—perhaps thinking Cheng Ying was some kind of Doraemon—came to ask, "You seem to sell everything… Do you have anything that can make food taste better?"
Cheng Ying thought for a bit and told him to come back in a few days. Then he fermented soybeans and wheat to extract monosodium glutamate (MSG). Though not very pure, even a small amount could make a bowl of plain soup taste amazing.
The cook was instantly blown away. In no time, he became a famed chef in Tian Dou City. But his glory was short-lived. Once Cheng Ying deemed the publicity sufficient, he began publicly selling MSG. The chef lost his unique advantage but was too embarrassed to blame Cheng Ying.
After that, many smart people realized this little shop wasn't ordinary. They started treating Cheng Ying like a real-life Doraemon, coming to him with every odd idea.
Someone thought fruit wine tasted awful, so Cheng Ying gave him a tiny bottle of glycerin.
Someone complained winter was too cold and heavy cotton clothing too bulky. Cheng Ying bought hundreds of ducks, drew up a design, and hired tailors to make down jackets that showed off one's figure even in the cold.
Someone said two-wheeled carts carried too little and asked for a way to increase capacity. Cheng Ying gathered his carpenters and taught them how to make four-wheeled wagons, which were soon in use.
One day, someone even asked him, all sneaky-like, what to do if they wanted to do "that" without getting pregnant. Cheng Ying, face dark, used a sheep intestine to make a condom, threw it at the guy, and told him never to ask such things again.
Then the next day, a woman came blushing, asking what to do when her period stained everything. Cheng Ying nearly exploded on the spot but maintained gender equality, made a cloth pouch filled with ash and herbs, and handed it over, stating that his shop wouldn't sell such items—if anyone wanted to mass-produce and sell them, they were free to do so.
Over time, people came to believe Cheng Ying was incredibly capable able to solve nearly any problem. And if he couldn't solve it outright, he'd at least come up with a practical improvement.