If you're made a fake emperor, why did you change the country's name?

Zhao Yu unexpectedly transmigrated into the body of a little beggar. He originally wanted to rely on his own strength to become a rich man, but he died before he could achieve his goal. He was kidnapped by a group of men in black, and when he woke up, he had become a fake emperor.
He walked on thin ice in the palace, clinging to the title of a fake emperor, deceiving everyone step by step until he finally unified the world!
"Your Majesty, you never used to come to my residence. Why have you come today?"
"Your Majesty, are these see-through stockings really appropriate? Won't they make the world say that I am not behaving like a proper empress, but rather as wanton?"
"Ah~ Ami's, Kurushi~"
"Yes, oh my god."
"Sawasdee ka~"