Mayumi, who lives with her son's family and her grandchild. Her grandchild entered university but didn't make many friends and stayed home. Worried, she planned a family trip, but her son's family had an urgent matter and couldn't go, so she decided to go with her grandchild. My cute grandchild has grown up so much. I'm happy that he gets an erection just by looking at my body. My body throbs in front of my grandchild's erect dick... I take the dick in my mouth and insert it directly into my grandchild. We will deliver a forbidden close-relative hot spring trip with a lifelong active, sexually voracious grandmother.