Despite the declining number of modern public bathhouses, four sisters continue to run a traditional sento passed down through their family. These beautiful sisters work cheerfully and energetically, captivating customers with their charm and doubling their business success. However, behind this thriving facade lies a hidden secret: all four sisters are lesbians, indulging in intimate, erotic moments with each other during work breaks and downtime. This film secretly unfolds their forbidden lesbian relationship within the rhythms of daily life.