Vampires love blood but it's not only vampires who love blood, there are also the Dragons that lives by using humans. 
The difference is? They don't just drink human blood, they eat the human as a whole not by flesh but by it's energy. 

Any human will do, but only few humans in the world carries this specific gene that taste so good for Dragons. They don't just satisfy them but mere touch would make them Stronger than other dragons.
These humans are what they refer to as "crescent", it is said that when a crescent gives his/her energy fully to a dragon he/she ascends to a next level type of dragon. Sandara Park continued to live in hiding ever since she learned about her families lineage, what's the problem with her bloodline? She's a freaking crescent!.  

What would happen if Dara runs into the wealthiest bachelor in asia, the heir to the Kwon Conglomerates a human but can be called a demon because of his cold personality. Can GD protect her from the Dragons? Yes, he's hot and mighty but he's a mere human. She did not just run into him but happened to ruin his lamborghini aventador!! OTTOKKE!!!