Lyric

An unsolved brutal murder case that shook the world a few years ago. And now, breaking the silence of time, a murder case by the same criminal has reoccurred.

The letter "Z" left on the murder scene ... The "Z" is an acronym for "ZERO" and indicates a message from the criminal that "I leave no trace on the murder scene".

The investigation was conducted by elites from the Metropolitan Police Department's First Investigation Division, centered on a 28-year-old male detective who is a martial arts specialist and a 26-year-old female investigator who is a expert in profiling... and the male detective and the female investigator were once lovers.

While the profiling investigation of the female investigator was getting stuck on, the investigation of walking around the murder scene of the male detectives beared fruit, and for the first time he grabbed a clue to the criminal. As if to be drawn to the clue, the male detective went to catch the criminal alone... but who was waiting at the place was the female investigator of ex-lover.

And they both fired each other's guns, as if the red thread of fate had unraveled ...

It is a song based on HR/HM that depicts the world view of such a story with a melancholy bluesy sound (like expressing sadness).