This is a romantic comedy series about four boys at the ages of 9, 19, 29 and 39 who each confront different challenges in love and work at the cusp of a new decade in their lives.

No Mu-jin is a labor attorney who happens to see ghosts. After coming back from the brink of death, he begins solving labor problems requested by ghosts.

When a devil-worshipping criminal network plunges Seoul into chaos, the police turn to Holy Night—a trio of supernatural demon hunters—to restore order and defeat the rising evil.

A psychopath's ruthless serial murders have left the entire nation gripped with fear and chaos. A honest and justice-seeking rookie police officer and a veteran detective with tragic past, face against the killer. After the encounter with the psychopath, their lives totally change.

Special episodes of "Mouse" which will highlight the hidden narratives in the series that the audience may have missed.