My father remarried and I, an only child, got a new sister. My sister, who came to live with us, was defenseless and showed me her miniskirt panties, but after she noticed that I was staring, she brought her plump ass in front of me as if to tease me. When the whole family went out and we were left alone at home, I ordered her to give me a massage, and as I rubbed her big ass, she got excited. Of course, her panties were completely visible, so my dick was rock hard. My tsundere sister was in the mood and taught me all about sex, so I gave her a hard-on with my teenage dick.