A trip with my teenage son was a special time unlike our everyday life. Usually cautious about my husband, here we could spend time together like lovers. Excited by the mixed-gender bath, my son invited me to the outdoor onsen. His hands gently touched my body, and I was deeply moved by his warmth. His cock throbbed hard, and even after ejaculating once, it quickly got erect again. Overcome by desire for him, I inserted fingers into my wet pussy in our inn room and made him cum inside me...