Here is a song titled "Goodbye", sung by Korean singer Zero. Without any badass Korean reading skills, I have the hardest time finding anything out about Zero, outside of a couple songs uploaded on Youtube. But I heard this song on a South Korean drama, Beautiful Days, and simply couldn't get it out of my head. Listen:
I wouldn't recommend the drama Beautiful Days to anyone; I didn't finish it myself. I don't even know if the main female character lived or not -- worse, I can't bring myself to care. But I love this song, even years later. Listening to it makes me feel a little heart-breaky. Perfect for a rainy day.