Floating in the middle of the River Sanzu in the underworld is the hotel Lost Stella. Unable to pass on due to his "unjudgeable sin", Kuroda Yasuhiro is stuffed into a maid dress and stationed at this hotel to work it off. Awaiting him there are Lost Stella's mysterious owner, and its guests who, like Kuroda, are burdened with their own "unjudgeable sins".