Ichiban Janakya Dame Desu ka?

A slightly old-fashioned wooden apartment called Ittokikan (Maison Ittoki) lies at the top of a gentle slope located nine minutes walk from the train station. It is a place inhabited only by girls who are disappointed with their male siblings. Shou was to be a new resident, but naturally he was refused entry to the apartment. However, he was able to open their hearts with his initiative and positive disposition and was accepted into their group. In turn, they became lovestruck with him and it was suggested that he become an older brother figure to everyone in the household. This prompted the declaration by his non-blood related imouto Hisui that she will stop being his imouto. Could they be satisfied all being second for his love?