Following excerpt is from "Peach of Time" site. I thought of sharing it, as it further explains the story of this well-produced series.
"To make it worse, Yun-oh doesn't realize this fact himself! How is it possible? Yun-ho is a ghost?! Does it mean that all this time, Yun-oh's mother had no idea her son was around?!
As if the situation was not complicated enough already, the pair meets another ghost! Mario, a young Thai man reveals to them that he died at the age of 24, back in the 90s when he first visited Korea. But why is he still in this world?
Mario knows how to pass to the afterlife, but he himself is not able to leave just yet. What keeps him bound on earth is a girl, Soojin, the love of his life.
Peach and Yun-oh put their heads together to figure out why Yun-oh is still here, and, most importantly, how to help the latter leave this world. They soon realize: Yun-oh's unfinished business is the bucket-list he had promised himself to fulfill as soon as he becomes an adult.
But for a soul to pass peacefully to the other side, one needs to fulfill unresolved matters in 49 days after one's death. They don't have much time left. After all, they risk Yun-oh becoming an evil spirit stuck in this world, forever!"