Soul Binder

About
Soul Binder is a Forbidden Youkai that has been sealed away due to the deadly curse that she transmits to people who touch her. Physically a short, white haired girl that does not talk, she doesn't transfer the curse of her own volition. A victim of her own abilities, as soon as a human touches her, he or she is cursed. The curse kills the person but traps the soul inside until they've touched 5 other people (which spreads the curse), at which point their souls are freed from their corpse.

When she was last released during the Youkai uprising (thanks to Omachi), she caused a pandemic that was only resolved by burning the bodies of the cursed en masse. Eventually Omachi was beaten by Masamune, who allied himself with the Oda clan's head (Kouhime's father) and he sealed Soul Binder up again. One of the victims back then was Nobunaga's father.

The next time she was freed was due to Kurohime, thanks to her father's pressure. This resulted in widespread casualties within the JAPANese population. Eventually, Rance had her sealed up again, although he was disappointed that he couldn't sleep with her due to the curse.