Shota and big sister Miyu were studying together, looking at an encyclopedia, but Shota was more interested in Miyu's soft breasts than in studying. Pretending to listen to her explanations, he kept touching and groping her boobs, playing his usual prank. He even showed her a video of insects mating, begging her to teach him about sex. After enduring Shota's relentless teasing, Miyu finally couldn't take it anymore and started feeling pleasure…