Set in the back-alley bar rooms of Tokyo's Ginza district, the film tells the story of Keiko, a "mama-san," or bar proprietress whose work is to entertain men for money. A thirty-year-old widow, Keiko realizes that she is at a stage in her life in which she must either remarry or own her own business. Refusing to descend into prostitution yet besieged by the furious competition of other mama-sans, Keiko attempts to borrow the money she needs to continue without a male "sponsor," but her plans change when one of her customers proposes marriage.