My step-sister, who was born when my parents remarried, is my favorite! Even though we're step-siblings, I try not to get weird, but she keeps clinging to me, so I can't help but get an erection with her big tits pressed against me and her panties showing every day! My step-sister wants to get along with me, so we even take a bath together and get close, so I can't hide my erection! But she reveals her true nature, saying, "Even though I look like this, I like sex," and takes my dick in her mouth! In the end, she turns into a slutty girl who forces me to cum inside her with a forceful double-lock!