Spoilers I want to tell you that next 2 or 3chapters there is a sence when cain and jooin wearing traditional korean costum and cain said " you look the same from that time" or something similar to that to jooin. My theory is cain has a connection with the past or have supernatural power and jooin is his master that time. That why when cain saw jooin first he call him master. I don't know that is just my theory and i don't see supernatural tag to this manhwa or yet.
Spoilers
I want to tell you that next 2 or 3chapters there is a sence when cain and jooin wearing traditional korean costum and cain said " you look the same from that time" or something similar to that to jooin. My theory is cain has a connection with the past or have supernatural power and jooin is his master that time. That why when cain saw jooin first he call him master. I don't know that is just my theory and i don't see supernatural tag to this manhwa or yet.