Yoshiko, a newlywed, finds her daily life with her husband Yoshiro so dull and passionless that she struggles to satisfy her sexual desires. One day, her brother-in-law Masao visits the house, and when she accidentally catches a glimpse of his huge cock, her heart is completely taken by him. Night after night, she obsessively fantasizes about Masao, indulging in masturbation. When Masao visits again, Yoshiko can no longer resist her urges and finally acts on her desires…!?