お姉ちゃんの3乗（きゅーぶ）

College student Arisaka Miku lives alone with his cousin two years his senior, Shunzaki Nanatsu. The pair spend their school days as any would until one day, a mysterious distortion in the space-time continuum splits Nanami into three girls. Their names, looks, and personalities are all different but they are certainly still "Miku's older sister". Then a fairy from another world comes to investigate the distortion... So begins this strange tale of cohabitation with three times the [i]onee-sans[/i] and three times the pampering! [Based on synopsis from the [url=https://web.archive.org/web/20110224160534/http://www.marron.nu:80/web/product/sis_cube/index.html]official website[/url] and back of game box]