What is the Ghost Doing? (귀신은 뭐하나 / Gwisineun mwohana)

Cheondong got dumped by his first love Murim 8 years ago. He's on the verge of getting sick of his boring life when Murim appears in front of him as a ghost. Even before he could accept Murim's death, Murim asks him for a favor. It's to find her boyfriend. Cheondong gets angry at first but he ends up looking for her boyfriend.