Surprise! This King Went to School on Earth

(Transmigration + alternate history + farming + world conquest + one heroine)

Six-year-old Xiao Yu, heir to the title of Prince of Han, and his personal bodyguard are sent to Earth in the twenty-first century by a jade pendant.

Just as he's about to graduate from university, the fully charged pendant takes him and his bodyguard back to their original world.

But what he finds is a princely estate under attack and a younger sister about to be sent away for a political marriage...

With no other choice, Xiao Yu puts what he learned on Earth to use, making money, stockpiling grain... and then stockpiling guns!