The cute high school girl sister, who was born after her mother remarried, is excited in a pretty defenseless outfit! ! But even though I'm a step-sister, I keep my excitement down, but I don't know what I feel, and my step-sister, who is at an age where he's too interested in sexual matters, will start to mess with me when his parents are there! What's more, he plays a quirky sexual prank! ! At first I managed to hold back, but as the prank gradually escalates, I finally got a full erection! ! After getting an erection, I couldn't hold it in and crossed the line...