Responses
Spoiler...
It is said in chapter 5 that after Ji Hoon came back with Gi Tae and cut Gi Tae's leg, Gi Tae couldn't handle the shock of betrayal and begin to harms himself... It was so severe that, one day, Gi Tae woke up with no memory from these 9 years after a several repetitions of waking up and fainting.
Ji Hoon was afraid to tell the truth because Gi Tae's conditions were bad back then. Ji Hoon was afraid Gi Tae would harm himself again.
So I understood there was going to be a plot twist, but to that degree? Hell, now I'm just wondering why he never told him anything when he did wake up or whatever. Really just made it harder for the both of them for. No real reason