A massive underground cavern, unseen by human eyes, and the mansion within it. A young girl raised in this lightless world lived peacefully with her beloved father and their servant. As time flowed gently, the girl — Claritte — grew into beauty, and it seemed their days of tranquility would last forever.

But when her father, Clemence, collapsed from a mysterious illness, the peace of their dark mansion shattered. Determined, Claritte shut herself in her father's study, searching for clues to cure his illness. There, she discovered a strange book revealing the existence of a unique rose that could cure any disease. This rose existed only in the deepest part of the mansion, but reaching it required overcoming several "trials". The book warned that even if she attempted the trials, failure would bar her path to the rose, condemning Clemence to die from his illness.

One day, as Claritte grieved for her sick father, the servant Ludoana informed her that Clemence's condition was worsening. Resolved to save him, Claritte saw the strange book point the way to the trials. Seeking the rose, Claritte plunged herself into the darkness of the trials.

[Translated from the official site]