Momohime is the female lead of Muramasa: The Demon Blade, driven by the evil spirit inhabiting her body to seek out the 108 cursed demon swords. She then uses the powers of those swords to inflict massive-damage on anything that stands in her way. From Ignition's character description:
Possessed by the spirit of a foul swordsman, this young kunoichi is forced to carry out its devious plan against her will. Described by her subjects as "beautiful as a flower and pure as the snow," Momohime lived her life as the Princess of Narukami. When a dark spirit comes to visit her castle, Momohime's idyllic life is changed forever. Forced against her will, she leaves behind everything she knows in a quest for the cursed demon swords…
Be sure to watch the trailer all the way through to the end, where we get to see some of the hot spring fun we've heard so much about.