My girlfriend has almost no interest in sex, so the weekend I expected to spend fooling around at her house looks destined to become nothing but movies and games. Then her voluptuous adult sister Yuka comes home—the exact opposite of my girlfriend. I cannot stop staring as she bends over and blows air up her braless blouse with a fan. Yuka photographs me gawking at her breasts, then uses the evidence to draw me into increasingly sexual encounters behind my girlfriend's back. Before long, her devilish titjobs have me betraying my girlfriend again and again.