Kanzaki Kaito is an otaku highschooler with no friends. Deriving joy from just conversing with online girls whom he did not even knew the face of, he passes his days in solitary. But, with his father’s remarriage, he suddenly became family with the top beauty of the campus, Momoi Saki, and her gentle and busty little sister Momoi Sakura! Sakura instantly got cozy with him, but Saki totally despised him. Then came one day, where the daughter of a big financial conglomerate, Saijou Kirara got ahold of Saki’s weakness and threatened her. Noticing something off about her sister, Sakura turned towards Kaito for help. Will the loner and otaku Kaito be able to save Saki!?