(The plot is a little back and forth, but I'm trying to let all of you who read this know in detail about all the chapters that happened).
Park Ji Kang's grandfather, whose last name is Park Jin Young, is no longer young and is required to always be a man of the same age whose face, job, and status Jin Young deliberately stole to take revenge.
Not by killing, Jin Young did not want to avenge everything with all death.
Even his pretend father-in-law had to die at the hands of Choi In Seung's son, and stupidly at that time Jin Young didn't have the chance to talk and contact his grandson.
Even sadder, when Park Ji Kang told him that the man had received one of the hard hits due to the collapse of the mansion by making the back of Ji Kang's head get serious treatment until Jin Young had to get news two years after Ji Kang had fully recovered.