It was a wonderful morning the Yokodera and Tsukiko went to school together while discussing their plans later than day for the school festival then suddenly a pink-haired little girl showed up, then it accrued that she was Ponta's little sister named Emi. Emi kept calling Yokodera onii-san (big brother) and seemed very friendly with him but at the same time Tsukiko seemed not to like Emi very much and had a feeling that she is a evil-plotted person,then she said that Yokodera should take Emi for a tour of their school and would wait for him afterward for their practices.Emi learned that Yokodera is a well-known "pervert" is his school so Emi took out a Cat-statue-figure like the one found in the storehouse of Tsukiko's house and wished Yokodera would be a "cool" guy in his school.　Weird thing happened, the school suddenly having Roman ancient architecture like the Colloseum, every girls in the school called Yokodera as prince and the school swimsuit as the uniform in the school.