The Essence Thief - The Essence Saga, #1

Sixteen-year-old Lee Soo-Yeon is haunted. Not by ghosts-though she does deal with them on a more than daily basis-but by a dream. A dream featuring a pair of chillingly beautiful golden eyes with vertical slits for pupils. She blames it on school-related stress and her inability to handle integrals, but then the number of ghosts in Busan dwindles drastically and an eerie presence surfaces in the boy she's loved for who knows how long.
Unable to glean answers from the mysterious being she once dubbed "Uncle Death", Soo-Yeon turns to desperate measures to gain information. That decision causes her not only to get involved with the city's most infamous delinquent but also the most beautiful boy she's ever had the fortune-or misfortune-of resting her eyes upon. V is charming, mischievous, unpredictable and secretive. He needs Soo-Yeon's help and is willing to exchange his knowledge for her aid.
But while Soo-Yeon thinks her request seems reasonable enough-she just wants to help the guy she loves-he wants to become human. For he's a gumiho. And he's willing to do anything to fulfill his wish.