During summer vacation, Erina, a female college student, returns to her parents' house. Erina, who was drenched in sweat from the intense heat, knew that the bathtub at home was not working, so she borrowed the bathtub at her grandfather's house following her mother's recommendation. Grandfather, who was annoyed by the sexy growth of Erina, who had returned after a long absence, could not suppress the strong desire that arose for the first time in decades and attacked Erina with momentum. . And he took advantage of Erina's weakness, saying, "In a rural area like this, if rumors spread, mothers won't be able to go out."