Today is the first day I went to my girlfriend's house. She lives with her older sister Misono, she is a nurse, often working the night shift. Whenever she is tired, Misono often falls asleep on the sofa. She also wears very loose clothes that expose her big breasts to my eyes. I have always tried to control myself, but when my girlfriend had to leave urgently, I couldn't stop myself anymore. I unconsciously approached her, my hand had been placed on her big breasts without me knowing. While fondling these big breasts, Misono didn't seem to show any signs of waking up. So I became more and more daring. Burying my face in these big breasts, sucking them, rubbing my dick against them, and Misono still didn't wake up! At this point, I could rest assured and proceed to insert my dick into her wet pussy...