[Sadrain]

A mysterious man main hero(ine) encounters and that comes and goes at his own leisure, always dropping mysterious hints. As the story progresses and then reaches the peak, it turns out that he is the soul of the main villain, now possessed, and while he cannot help directly, all he wants is an eternal rest... or punishment, whatever he might receive. Anything, but lingering around this world longer. If the hero(ine) has developed romantic interest in him, he might want to linger for longer, but is not granted the chance, leading to heartbreaking ending, but a glint of hope is given in epilogue, mentioning a reincarnation...

(I am sorry that I always make depressing things out of this avvie, Jurinjo. D: Must be the mask... >_< )