Since the death of their parents years past, Junna and Senna have been living alone in the big house their parents left them. Together they attend Sakurahama Private High School, where several select girls obliviously use and abuse Junna for their own needs–Kishida Tomo, pretty and anti-social; the booksmart and efficient Iida Akino; Ohtori Tsubasa, head of the Help Club and highly in demand; Fujie Sana, cute as a button but with the intelligence of a box of rocks. And then there’s the new girl, Inohara Haruhi–an old childhood friend of Junna’s that’s come to claim her “onii-chan” (brother). Strangely, Junna barely remembers Haruhi from his childhood…and Senna doesn’t want him to.