Taesoo was just a normal boy for his entire life. He was a friendly young man, sure— and flirtatious often, but he was pretty average, all around. At least, he was, until he got into a freak accident only a few weeks after he turned 21. The exact circumstances of this accident are uncertain, but it seems likely that it wasn't an accident at all.

As a result, Taesoo didn't exactly stay dead. Instead he came back as a ghost, with the weird urge to figure out what had happened to him. So he starts a bit of his own investigation, involving a few hauntings and scaring a few people along the way. His old friends didn't believe that he was real or assumed that he was some weird avatar of guilt, which made him incredible sad for a while. But eventually, he makes attachments to a couple of friends who become extremely interested in his plight, and they help him get a little closer to the solution he needed.

However, they eventually hit a dead end, and so even though Taesoo had really liked this pair of young people, he had to find another pair of people, with a different set of skills, preferably a little older and experienced. At this point, several years had passed, and one of Taesoo's old friends, who he had went to before, had become a police officer. He figured he'd go back to him, and see if this time he'd be more willing to help. At least, until he learns that said police officer had gone missing.