My older sister, who got married and left home, suddenly came home saying she was going to live here for a while. It seems she wasn't getting along with her husband's family. As a virgin, I'm worried that I'm too nervous in front of my girlfriend and can't do anything. One day, my older sister saw me studying how to have sex on the internet. I quickly tried to cover it up, but she smiled meaningfully and said, "I'll teach you properly next time." In the end, my older sister, who had made up with her husband, was in a good mood and took off her clothes in front of me.