Devoted wife Satsuki is forced to work as a hot spring companion at a rundown bathhouse to pay off her husband's FX trading debts. In front of her husband's eyes, she is subjected to sexual acts by the inn's owner under the guise of "training," enduring deep humiliation. At this seedy hot spring, she is compelled to serve vulgar long-stay guests day after day. With a growing number of clients and their varied demands, Satsuki gradually hones her skills—eventually mastering the exceptional techniques of a premier bathhouse mistress.