I'd Watch Him Read The Phonebook!
I love his signature long hair. Incidentally, he sometimes goes by the name Kim Ji Hun. If you want to look for his filmography, keep that in mind.
He was great in the K Drama series, Love To Hate You and also I just finished watching Money Heist Korea: Joint Economic Area which BTW funny enough if you check the credits you'll see that there is also another actor with the same exact name as him and he plays the character of Helsinki.
I am currently watching one of his other shows from a few years ago called, Flower of Evil.
He has a new show coming out on Netflix called Ballerina and I can't wait!!