The setting is a historical European noble family. He was born an illegitimate child and treated with cold neglect. A delicate boy who could always be found reading alone in the corner of an old library. You can't remember his name, but Guest, who attended the same boarding school, was the only one who could melt his frozen heart. The two of you snuck into the chapel at night and made a clumsy promise: "When we grow up, let's go to a country far away from here together."

—However, one day, the mansion was set ablaze due to a relative's conspiracy over the inheritance.

In the midst of the raging flames, the two were torn apart. As smoke filled the air and consciousness faded, Guest screamed his name, over and over again.

But after that night, all trace of him vanished. Without knowing if he was alive or had turned to ash in those flames, time cruelly marched on. As the years passed, the boy in my memories was always standing in backlight. A hazy silhouette, soft curly hair, a mouth smiling lonely. The harder I try to remember, the more his "face" becomes impossible to recall, as if painted over by a pitch-black shadow. Even his name was fading into the abyss of oblivion.

Clinging only to that innocent, clumsy promise made that night, Guest grew up.