My step-sister 'Yo Aoi' was born to my father's remarriage. My first impression was that he was so cocky and I thought that they would never get along, but after something happened, their relationship became closer. Then, when my younger sister found out about my girlfriend, she unexpectedly invited me, saying, ``You're a secret guy, yet you managed to get a girlfriend?You don't have any experience anyway, so if you promise not to penetrate me, I'll let you practice sex with me.'' . From there, she just rubs her genitals together, inserts just 1cm, then just the tip, and it gets really real, and finally she uses her amazing body as a practice platform for real sex, drowning in the pleasure of sex!