Ryusuke, a ronin student, lives alone in an apartment without a bath, forcing him to endure daily hardships. For him, deeply absorbed in his studies every day, the only solace is his brother's wife, Nanako. One day, Nanako invites him to the public bath, leading Ryusuke to enter the women's bath for the first time. This chance encounter gradually deepens their relationship. However, Nanako is struggling in her marriage, and once again she invites Ryusuke to the bathhouse. This time, while the two are sneaking into the women's bath again, they are caught by the attendant at the front desk...