Nae Joseone Sejong-eun Eopda

I opened my eyes to find myself in Joseon, reincarnated as Grand Prince Yangnyeong, the eldest son of King Taejong. His fate is to be deposed as Crown Prince, while the throne is destined for his younger brother Chungnyeong, who will later become King Sejong. But I am a reincarnator. Armed with knowledge of the future, I will build the Joseon that Sejong was destined to create—before he ever can.

“I'm sorry, Chungnyeong. There is no Sejong in my Joseon.”

(Source: Naver, translated)