After her sister Bertha's death, Lucia Nicol is struggling to follow her footsteps.

She becomes a self-centered person who will do anything to replace Bertha's position in her family. Her actions made her schoolmates loathe and bully her, thus leading to an unexpected event. One by one, the schoolmates who once bullied her were now attacked, and suddenly she became the main suspect. After those events, she found out that she was able to see people who can’t be seen by “normal” people, and that she had the ability to uncover the dark, insane truth of an entity called “Doppelganger”.

Her life is suddenly in danger, and the people she normally trusts suddenly doesn’t look so kind any more…

[From Lemmasoft forums]