As a tunnel construction project threatens the natural order of one of Japan's last untouched regions, an old man and his granddaughter Haruna's humble lifestyle begins to influence the outlook of a man from Tokyo.

Ninko is a virtuous Buddhist monk who’s embarrassed to discover that he’s irresistible to many women (and some men). After a particularly troubling encounter with a masked woman, he undertakes a journey to "purify" himself, hoping that this will equip him to rebuff sexual advances. He meets the samurai Kanzo and hears of a village decimated by the rapacious mountain goddess Yama-onna, who kills men to absorb their energy. Finally Ninko has a quest to fulfill…