Shuri Yamaguchi lost her husband and raised her daughter alone. Her daughter grew up successfully, got married, and continued living with her. One night, during an otherwise ordinary and warm family life, Shuri accidentally spied on her daughter and son-in-law's private moments and was deeply shocked. Her son-in-law, despite appearing serious and reserved, was passionately and intensely enjoying sex. Witnessing this awakened Shuri's long-dormant sexual desires, unleashing an uncontrollable lust within her.