Yumiko had been dreaming of a perfect summer day at the beach with her husband, filled with joy and excitement. However, when he couldn't join them, she found herself heading to the shore alone with her young son, her spirits dampened.

Feeling downcast on the sandy expanse, her day took an unexpected turn when two young men approached her. Later that evening, after putting her son to bed, Yumiko felt a secret thrill as she accepted an invitation to the room of the men who had flirted with her earlier.

Torn between guilt and the rush of forbidden desire, Yumiko embarked on a steamy summer night that marked the beginning of an illicit and passionate affair...