Kisaragi Maaya is our protagonist’s (Yuu’s) older sister. She’s beautiful, smart, and super popular at their school to boot. Yuu cherishes his sister more than anything else in the world, and Maaya treasures her little brother more than anything else in the world in return. Maaya always had a knack for teasing Yuu, but at some point, it gets a little out of hand, to the point where her at first innocent teasing becomes flat-out flirtations, slowly leading towards a carnal relationship. Yuu has always been a pushover, and can’t do anything but follow along the path his big sister is creating for the both of them. Maaya’s outgoing personality and charms eventually win the day, and a full-blown sexual relationship starts between the two siblings. This is a slice of life story filled with lust, and worry-free summer days with lots of sex, and an ending full of happiness.