Takeshi Kitamaki, a handsome and disciplined 26-year-old, leads a life of quiet anonymity, a stark contrast to the life of his younger sister, Ayumi. At 25, Ayumi Kitamaki is a national sensation, the stunning, black-haired center of the top idol group, "Mikuyi." Alongside her equally charming bandmates, the chic Izuwa Manasaki and the elegant Hina Ojori, Ayumi has captured the hearts of millions.

But here's the secret: while the world worships Mikuyi from afar, the three idols live with Takeshi, treating him as their beloved older brother. At home, the glamour fades, and they are simply family. The problem? No one, especially not the gossiping fans at Takeshi's own university, knows of his connection to Japan's biggest stars. As Takeshi navigates a world that is obsessed with his sisters, he finds himself at the center of their affections, a quiet battle for his attention brewing between the three women who see him as more than just a brother.