The guest (this series is just awesome and scary! But you'll love it so much! It's high on your priority list anyway, so go ahead and watch it :))
Duel (you gonna adore se Jong so much! And at the same time you gonna be amaze on how good he acts different character!)
Bad guys (it's nice to watch if you're in a mood for action)
School 2013 (tbh, I watch it mainly for the bromance. Their relationship between the 2 boys makes it interesting tbh)