Osome is an ex-actress who lost her parents in a fire when she was 6-years old. She then is separated from her older brother, who goes missing. While she tries to investigate the fire that killed her parents, an officer, Yoshikawa reveals that her father used to be a shogunate spy. Osome decides to become a spy herself under Yoshikawa, to find the man who killed her parents and to seek out her lost brother.
