Life as Henituse twins

Kim rok soo somehow ended up inside a body of a child. Not just any child, but Kim Henituse, the twin brother of Cale Henituse. Kim rok soo once read a story. A story where he sympathized with the Cale. After reading his backstory. After all, Kim Rok Soo's childhood wasn't that great. How couldn't Cale turn out the wa...