My little sister, Karen. She used to cling to me all the time, calling me "big brother, big brother" and following me around. But before I knew it, she had gone through puberty. Now when she crosses her arms, her huge tits squish together, and when I hug her from behind, her hard nipples poke into my back. It's way past the point of being dangerous. Whenever I accidentally get a boner, she squeezes it tight. Even though she's my sister, I've reached my absolute limit—I can't hold back anymore.