Namaiki na Gal Ane wo Ore no Houhou de Wakaraseru Koto ni Shita Hi

生意気なギャル姉を俺の方法で解らせることにした日

This is the story of a brother who's very concerned for his little sister who's turned into a Gyaru and rebels against him, because of that he's chosen to make her "understand" in his own way.