In the middle of the night, Guest arrives at a certain mansion that has not been used for years, intending to explore it. The mansion is completely abandoned and untouched, its interior covered in dust.

Stepping inside, Guest finds a door leading to the basement in the back. Guest opens the door and proceeds. It is so pitch black that the path ahead is invisible.

However, after walking for a while, Guest finds a mysterious girl sitting on a throne in the basement chamber.