I was seduced by my girlfriend's older sister Ranka and it ended up that Yuki was having a good time with his girlfriend, but every time he had sex, his lover wouldn't let him play naked and had to use a condom. rubber. Then one day, he met his girlfriend's older sister named Ranka and a miracle happened. A sassy girl who couldn't care less about condoms or whether he was her sister's boyfriend took the initiative and the two secretly flirted with each other during the days this guy was here. How will everything turn out?