I'm Miyanaga Rikuto. A second-year high school student whose age equals the number of years I've been single. This spring, I, a guy with zero immunity to girls, suddenly got a stepsister. And not just one, but five of them!? The eldest daughter, Chinatsu, absolutely hates men. The kind-hearted second daughter, Mio, and the gyaru third daughter, Karin, are twins. The fourth daughter, Fuuka, is an ojou-sama with a secret, and the youngest, Sorane, is a total spoiled brat! This sudden cohabitation is the start of a chaotic life full of trouble!