Natsuno Shinji spent days helping with a coffee shop of Ai his older sister while going to school, the situation changes completely by becoming friends with popular school girl Matsunaga Shigure!

Ai with extreme brother complex and older sister Kamiya Aoba of the childhood friend, it has mistaken Shigure as a girlfriend and to get Shinji back, lewd tease and education are begun.

In addition, mother-in-law Utako who starved for family's love and Shigure who must have been a friend... participates for some reason!? A lewd mischievous education life of the Protagonist begins!