Prior to Reawakening, Jin-Woo was a kind, nervous, and very a timid young man. He respected his fellow Hunters and was brave enough to continue fighting in Dungeons in order to earn money to care for his sister and to pay for his mother's medical bills.
Jin-Woo is also shown to be an intelligent person, being able to stay calm under pressure as he figured out the clues to fighting the boss of the Double Dungeon while most of the experienced hunters in their party panicked and were killed by the statues when they were trying to escape.
Jin-Woo is the eldest child in his family. After his father, Sung Il-Hwan, disappeared inside an unknown gate, Jin-Woo took all the responsibilities for his sister, Sung Jin-Ah and mother.
He worked as an E-Ranked Hunter under the Korean Hunters Association for 4 years, then after the Double Dungeon incident, Jin-Woo became a Player and a Reawakened Hunter.
Jin-Woo expereienced "ReAwakening", a hunter's second wind of power. His was vastly different, given it was his death that brought it about. Jin-Woo became a Player as well, similar to that in any Role Playing game. His stats became visible to him, as well as being improved upon vastly. The "System", as it's referred to, continually spit daily quests at him. Each quest passed earned him more power. It wasn't long before he was capable of completely decimating the dungeons he'd previously been on the verge of death in.
Nearly everything about him changed after his "ReAwakening". Jin-Woo became hardened, focused, and sadistic while hunting in dungeons. He's able to distinguish between the dungeons and the real world, keeping his previous kind and caring demeanor. The changes he underwent made him far more sociable as well and he quickly made both friends and enemies.
Ten years ago, dimensional rifts that were given the name "Gates" opened up all over the world and a certain percentage of the population were given superpowers. Those that were given that power became known as Hunters. Both the Gates and the Hunters were given ranks based on difficulty and abilities respectively. It's very much like a RPG, except the Hunters have static abilities. Their skills are set once they get them and can't really be improved.
The Gates also have a difficulty curve. From E to S rank dungeons, where an E rank dungeon would have maybe cat sized insects or a small group of goblins. An S rank dungeon would have extremely intelligent and overwhelming armies of powerful High Orcs, Ice Elves, Demons, etc.
Jin-Woo is described as the #4 National Rank Hunter. National Rank Hunters are said to be capable of rivaling an entire country's military might. Two S Rank Hunters, below National, fighting would be devastating to the country they fought in.
