When I went back to my parents' house for the first time in a while, my little sister Yui was in full tsundere mode! Even though she loves her big brother, she gets angry and sulks, which is so cute! She gets angry when she sees my defenseless panties. But then I found Yui smelling my underwear and masturbating! Yui came on to me and said, "But I love you, big brother! Do you have any complaints?", so we had sex!