Satomi Shijima is an agent of the investigation company Augen und Ore.
Making full use of her "feminine weapons," she easily completes her missions, but
is given an urgent investigation mission. It is an undercover mission in Yamiya City, her hometown, which she left 10 years ago.
A series of disappearances have occurred at Yamiya Academy, her alma mater, and
human trafficking is lurking behind them. Satomi infiltrates
the school as a part-time lecturer to monitor teachers suspected of involvement, and has an unexpected reunion with
her biological sister, Ema Ajima , whom she separated from 10 years ago... But the intentions of the vicious criminals, Satomi, and Ema become intertwined, and the sisters are trapped and sunk in the cage called the school... Is there any way out for the two of them who are being crushed by humiliation and pleasure?