House Mayton's Youngest

As the author of "Swordmaster Sade", Cha Sung-Min had no idea how dangerous his plot-hole-riddled novel could be until he's reborn as Rasen Mayton, a spoiled side character destined to die at 17. As if being stuck in the body of a rude scumbag despised by everyone wasn't enough, Sung-Min also discovers that he was reborn at a point before his story began. With almost no knowledge about the current timeline, will Sung-Min be able to survive in this unwritten world as House Mayton's youngest?

(Source: Tapas, edited)