- Yoon Woo hyun is one of the Four Guardians of Heaven, the "Blue Dragon". He is also one of the two Guardians ordered to capture the angel princess. When they were all little, Woo-hyun teased Ah-hin while thinking that she was Ee-jung because he had a crush on her. Even after a few years, Woo-hyun still likes Ah-hin and tries to make it up to her even with her bitter rejections and Ee-jung's cold warnings. He is also one of the students at Dong-young's school and hunts down evil spirits with Doh-hyun, his cousin.
- Probably one of the most energetic of the group next to Dong-young, but at times can be seen as serious, such as when he threatened to fight the Princess in order to return her to Heaven. At times can be perceived as naive or even lazy, but cares deeply for his friends, especially towards his cousin Doh-hyun.
Woo Hyun has short red hair and eyes. At the start of the series he keeps his hair back with a hariband but changes this in an attempt to impress Ah hin (which fails). Like all heaveners, he is very good looking (especially as compared with humans), as can be seen whicn he obtains a girl's phone number after she also pays for his burgers when Doh Hyun runs out on him at the restaurant.