Akito and Akiko Himenokouji are brother and sister, and were made to live with different families for six years following the passing of their parents. However, they have reunited at last and are starting to live together. It's clear quite soon that Akiko is in love with her brother, but Akito simply sees her as a sibling. Akiko's expectations of living alone with her brother are dashed when three more girls—Anastasia Nasuhara, Arashi Nikaidou, and Ginbei Haruomi Sawatari—move into their flat. Even more challenging for Akiko to get her brother's full attention is the fact that these girls like Akito in some way as well. The girls engage in various eroticisms that could be a little too much for a regular guy to bear as they argue over who should look after Akito.