Imouto ga Heya de Onani Shiteru Genba ni Fumikonde Osoi Kakaru Ikenai Onii-chan

Me and my little sister watched the house while my parents were out celebrating. It got late, I figured my sister went to sleep and checked on her. But outside her door I could tell she was awake... and... ... Masturbating? I burst in and caught her in the act. She couldn't deny it. But I also didn't want her to stop. In fact I wanted to join her. I took off my clothes and showed her my erect d*ck. She seemed ashamed of what I was doing but was obviously fascinated. She couldn't take her eyes off it. As instructed, she touched it. Then I rushed her. My sister gave up the fight pretty quick. Her body was mine to enjoy until morning. Over and over I let out all that pent up cum.