My father remarried my single mother and suddenly I had a sister. I wasn't even used to living with the four of us yet, but my parents went on their honeymoon, so I ended up living alone with my sister-in-law. I have to study for the entrance exam, but I can't help but be curious about my half-sister-in-law's big ass! I was so excited to see her big ass sticking out of her denim shorts that I couldn't resist and creampied her right away! I thought I was going to have sex with her, but she refused to have sex with me, so I begged her to pull out with my mouth. My sister-in-law's blow job felt so good that when I ejaculated in her mouth, she swallowed it. I was even more excited that he had swallowed my sperm, and my erection could no longer be subdued. During the few days my parents were away, I put aside studying for the entrance exam and had my stepsister suck me and swallow my sperm many times!