Very common university student Mitsui Yuuichi. At present, it lives alone to go to university. She is not... I mean it is younger sister excitement love.

Therefore, "It reaches an act prohibited the way things are going", to leave with the younger sister, a university far from the parents family was selected brokenheartedly.

However, the day with summer vacation, a beloved younger sister visits in Yuuichi. The younger sister who saw after an interval of two years, pretty as it is, corpulent bust, pinched-in waist, the become tense ass was newly acquired.

Younger sister Hana who has this strongest visual. However, to her, there was only one fault. Only fault, it... terrible it is foolish. It is forgotten to have remembered if walking three steps one after another, the kanji can hardly be read, Remote control with three switches or more cannot be operated.

To bring up younger sister Hana like the danger even of the social life to a splendid adult, Yuuichi prepares oneself to walk in the thorny path.