Kohaku no Yume

Wishing that she had never even existed, Mishiro Usui left a suicide note detailing how much she hated her boring life before she threw herself into a lake at the age of 16... but of course, that's not the end of the story. When she came to, she was in the Mirror World, a dark and wet place that was neither heaven nor hell. She had no memories of herself, nor that of her name. Looking around, Mishiro then finds a mirror into which she looks into the eyes of her reflection. Suddenly transported into a familiar room, she explores, and finds a knife on the desk. Taking it in her hands, she ends her life, and once again returns to the Mirror World, standing before a shattered mirror. Then her reflection instructed her: "Find the mirrors in this world, and break them." She then learnt the only way to regaining her past, and maybe grant her wish, is to search for all the mirrors in this world and break them by ending her life in front of them all over again.