Taking her brother's provocation seriously and going berserk, the busty younger sister, Mitsuko Yakuno, went on a rampage, relentlessly thrusting her penis into him without even realizing it. (PPPE-429)

"If you only masturbate with your nipples, they'll become as hard as rocks!" This casual lie from her brother drove the naive sister into a frenzy! Feeling that her nipples getting hard was terrible, she decided to use her vagina to attract her brother's male hormones! After experiencing the pleasure of unprotected sex, even when her brother shouted, "I'm going to cum!" or "I've already cummed inside!", she was completely absorbed and didn't notice, frantically thrusting her hips! Completely ignoring the fact that he ejaculated inside her, and unconcerned about the overflowing semen, she only accelerated her hip movements!