Lee Saen

Lee Saen is the number one ranked hunter, until one moment...
Cha Yi Je is a first-rank hunter, well... effectively dead, as he was thrown into a rift and then thrown out seven years later. Ji is Cha Yi Je's call sign, and he was already considered dead. Also, no one knew his face, as he wore a black mask covering his entire face at all times.
Lee Saen was once saved by Ji, healed, and promised to take him to the sea when he recovered, but... he later disappeared into the rift. Lee Saen became awakened, gained strength, and recovered. He became first in the ranking (or maybe second... after Cha Euija) and believed that Hyun was still alive.
A couple of years later, Lee Sae-young met Euijae, and something incomprehensible drew him to him. A couple of months later, Lee Sae-young learned that Euijae was Ji-chan. He wanted to live a quiet life and... stopped being a hunter? If you can even say that. When the ratings were updated, Ji-chan went public, and people started looking for him.
Euge doesn't know that Saen is the boy he saved, since his face was all bandaged at the time, but Saen recognized Ji by the warm touch of his cheek...so familiar and unforgettable
Saen didn't say he knew everything. He just teased him a little and watched to see how long Euge could pretend he had nothing in common with the all-time strongest hunter, nicknamed "G. "