I Brew Pills in Japan and Build a Dynasty!

I was Lin Feng, a top student in modern chemistry. After a string of job rejections, I spent more than twenty hours delivering takeout. I ran a red light, crashed, and transmigrated into the Great Yan Kingdom as Wu Yan, an alchemist. The original Wu Yan had traveled to Dongzhou Island in response to the Dragon Emperor's Longevity Decree, seeking an ancient alchemy manual. He died after getting caught in a factional brawl between the Golden Flame Sect and the Blackwater Hall. I inherited his memories of alchemy and bonded with the Comeback System, which guarantees a way out in the direst situations. Drawing on modern chemistry and traditional alchemy, I use molecular theory to analyze medicinal properties and extraction techniques to improve pill-making. When factions hunt me down, the System activates a secret spiritual spring realm, helping me escape and find thousand-year-old medicinal herbs. When my pill furnace explodes, I unlock a heat-resistant formula and produce potent pills. I use alchemy to help the islanders caught in the war, and teach them to make cement, improve their farming tools, and build terraced fields using my knowledge of chemistry. When the factions lay siege to me, the System guides me to an abandoned mine, where I use metallurgy to forge weapons. When disease spreads, I unlock a disinfectant formula and save countless lives. Over time, I rally the people and unite Dongzhou Island's scattered factions, using the wisdom of two lifetimes to establish systems and spread knowledge. A once-wild land of bloody factional strife becomes a civilized nation with flourishing agriculture and trade, governed by laws and proper conduct. I answer the Dragon Emperor's request for medicine with an improved longevity pill. Under the name Wu Yan, I write a legendary comeback worthy of a soul reborn across two lives, becoming a revered founder of civilization.