Kota's mother passed away two years ago due to illness, and since then, his grandmother Shoko has single-handedly managed all household duties, supporting the family of three. Even after losing her daughter, Shoko continues to live earnestly every day, determined to spare everyone from hardship. Worried about his grandmother, Kota—affectionately raised as the doting grandson—plans a family hot spring trip and takes Shoko along. During their journey, Shoko finds her eyes drawn to her grandson's huge cock, and for the first time in ages, her pussy begins throbbing with excitement...