Ryuudo Yukiatsu is a 39- years old ronin in Edo period Japan. Unable to stay in one place for any period of time, he has been wandering for years, pursued by a mysterious vision. Recently escaped from the ghetto where rootless immigrants to Edo (called “floaters”) are forced to live, Yuki (as the locals call him) is working at a local bathhouse when he encounters a young boy who can see the very same visions that have plagued him since childhood. While attempting to help the boy and his mother, Yuki comes face-to-face with a youi, a demon thought to be “pestilence personified.”