It's like an adaptation of all the Zombie movies from around the world. In Z Nation, Murphy gets bit by zombies and got immune which turned him into a new breed; the same thing happens with "Yoon Gwi Nam".
Murphy has a little army of his own for a while, though Gwi Nam, doesn't have any armies, he bit two people which makes them a separate breed..
There are a lot more similar connections with a lot more movies, but let's stop here!
This Kdrama portrays loads of emotions, like students going through adolescence, teen-romance, friendships, sacrifices, and more. The story was good overall. Hopefully, I guess Season 2 will be better if there is one!!