During summer vacation, Erina, a female college student, returned to her parents' home. Erina, who is drenched in sweat from the intense heat, finds out that the bath at her house is out of order. Grandpa, who was upset by her sensual growth of Erina who resumed her after a long time, can not suppress her strong desire that springs up for the first time in several decades and attacks Erina with her momentum. And, "In such a rural area, if rumors spread a little, mothers won't be able to go out...", taking advantage of Erina's weakness...
