「ねぇ、見たよ!」私は彼女が自慰行為をしているのを発見し、彼女をイカせてしまいます

One afternoon, after arriving home, I proceeded to enter the study wanting to research something on the computer. When I opened the door, I was so surprised to find my stepsister uncontrollably tormenting herself. The unexpected thing was that she discovered me watching her and invited me in.