I started on a deserted island and encountered Ying Zheng, who insisted I was an immortal.

My plane crashed, and I was stranded on a desert island for three years.
With the seeds provided by the system, I transformed the deserted island into a vast farm, with potatoes and sweet potatoes piled up like mountains.
Until that day, three men in ancient costumes drifted ashore.
The imposing man at the head of the group stood up: "I am the First Emperor of Qin, Ying Zheng."
I laughed: "Having fun with cosplay, bro?"
I casually tossed them a potato to fill their stomachs.
Ying Zheng took a bite and suddenly trembled all over: "What is the yield per mu...?"
"About four or five thousand catties, the leftovers were all fed to the pigs."
"Thump—"
Marquis Tongwu of Qin, Wang Ben, immediately knelt down: "What a waste! This is a divine object that can save the country!"
I was wiping my bottom with scrap paper when Shangqing Mengyi rushed into the outhouse like a madman to save me.
I used a bronze sword to chop pork, and Wang Ben was so angry that he drew his sword and was about to fight to the death.
Until I pulled out a mahjong set: "We're one short, wanna join?"
Ying Zheng stared at the linen IOU, gritted his teeth, and pressed his fingerprint on it.
Later, I taught them how to eat hot pot, play cards, and brew Erguotou (a type of Chinese liquor).
They kept asking me about magic techniques every day.
Until one day, a dark, imposing fleet appeared on the sea.
Armored warriors knelt on the beach, shouting, "Welcome back to the court, Your Majesty!"
Ying Zheng turned around and grabbed me: "Sir, come back to Xianyang with me."
"I hereby bestow upon you the title of Marquis, and grant you half of the empire!"
As I looked at the thousands of soldiers kneeling in a row, the half-eaten sweet potato in my hand fell to the ground with a "thud".
"No...you guys are serious?"
At that moment, the system that had been dormant in my mind for three years suddenly activated—
[A connection to the nation's destiny has been detected. The survival system has been upgraded to... an empire development system?]