In an age when large-scale natural disasters frequently happen all over the world, when cyborgs and autonomous robots are beginning to appear on the market in technologically advanced nations, and major world powers compete for technology and resources, the divide between rich and poor grows and the future for the poor looks bleak. In this transitional stage, everyone wanders around in a self-indulgent daze and the way out isn't clear... This is the story of how two cybernetically enhanced girls meet.
Yuuta has always been close to his elder sisters, Chiyo and Chinatsu. The only man in the house, he falls in love with the caring and affectionate Chiyo; with her well-endowed body and love of cosplay, she gives her brother everything an adolescent boy could dream of. Envious of her siblings' intimate relationship, Chinatsu soon steps in, seeking Yuuta's attention. As a strong-willed and dominant tomboy, she is the exact opposite of Chiyo and starts picking on him and making aggressive sexual advances. With the situation at home changing dramatically, the siblings must find a way to sort out both their private and school lives and establish a compromise between conflicting interests.
Masayuki's parents have gone overseas, leaving him alone in the house. To his surprise, they have hired Sayaka, a fellow student from school, to work as his maid while they are gone. Masayuki wants his life to be peaceful, but alongside Sayaka's affections he also has to fend off the attention of his kohai, his younger aunt, and his aunt's yandere lesbian admirer.
It's finals time, but tests aren't the only things stressing out Yuuta, who's literally being smothered with affection from his beautiful sisters: Chiyoko, who is feminine, caring, and coddles him; and Chinatsu, a strong-willed tomboy who desperately seeks his attention by picking on him. Who will triumph in this sibling love triangle?
