This manga is based on the memoir "Towazugatari," known in English as "The Confessions of Lady Nijo." Lady Nijo was a historical figure who lived from 1258- after 1307. "Nijo" was the name given to her at the court of Emperor Go-Fukakusa. Her real name is unknown.
Nijo's mother died shortly after she was born, and she was taken in to be raised at court when she was 4 years old. The Emperor (15 years older than Nijo) loved Nijo's mother and transferred that affection to Nijo after her mother's death. The manga begins with Nijo at 14 years of age, when she is given to the Emperor as his concubine. The story continues with the difficulties and scandals of Lady Nijo's life at court. [tethysdust]