The Sickly Crown Prince is the Nation’s White Moonlight

No CP + System (of little use, mostly disappears in later stages) + Will not become emperor in the end + Sickly but not terminal. Yong Cheng’an transmigrated into a book, becoming the “civet cat” in a “Civet Cat Swapped for the Crown Prince” plot. In the original story, the fake crown prince was sickly from childhood and unloved; once the real crown prince returned, he was despised by everyone and eventually died of illness in the palace. By the time Yong Cheng’an transmigrated, the “Civet Cat Swapped for the Crown Prince” scheme was already a fait accompli. To save his own life, he spent his childhood dragging his frail body around, diligently working to earn the favor of those around him. Little did he know, he would overdo it. Everyone now regards him as the bright moon in the sky, showering him with boundless affection. When the real crown prince finally returned to the palace, this favor didn’t just remain—it doubled! — Description from novelcodex.orgFull novel: The Sickly Crown Prince is the Nation’s White Moonlight — read the rest free on N​o⁠v​e⁠l​C⁠o​d⁠e​x⁠.​o⁠r​g⁠