Hasuno Miyu is your typical second year middle school girl who happens to love her big brother Keiichiro so much. One day while walking home from school, she encountered a strange girl wearing kinky cosplay tied up into a tree. And now everywhere Miyu goes, she always finds herself bumping into that strange girl and her strange perverted owner. After narrowly escaping being caught, Miyu rushed home only to discover that the weird pair she encountered earlier was none other than her beloved big brother and a strange demon girl named Manimani.