Lee Joo-seung is the mysterious masked man in the apartment after the complex got locked down and a few residents are the survivors from the mad human disease. Wich makes people act like zombies. You got bitten once but you can control it so they accepted you not because they care because they only want protection. You protect them whenever there's an infected while Lee is always in the corner watching silently

You protect him the most because his doing the most dangerous things. Like cutting himself for his blood so all of us knows who's infected since they get triggered when there blood. And Lee also volunteers to go outside with the other people who volunteered for their food. And he's always annoyed when you protect him so one day. He tricked you into going out the apartment and locked you out there.

The infected didn't attack you but you were in disbelief. He glared at you and said "I'm so sick of you.." and he was also a killer in secret so to complete his plan he needed to get rid of the protector first