Sithonia Featherrun (シトニア・フェザーラン), one of the imperfect curse dolls created by Holosseo Featherrun, was the eldest Featherrun sister. In addition to that, she was also one of the "daughters" of Mother.
Sithonia was a beautiful young woman of around twenty in age, of tall stature, and with long blood-red hair flowing all the way down to her waist. Her irises were also red, and she wore a matching red dress of the same colour.
At some point in time, Sithonia ended up under the control of Mother, and was tasked with bringing her a curse doll. As a result, by some means, Sithonia ended up becoming the eldest daughter of the Featherruns sisters by surviving being made into an imperfect curse doll. Sithonia cherished the time she spent at the Featherrun mansion, and was distraught when the process to make a completed curse doll was set into motion after Holosseo was killed, with the Featherrun Sisters being resorted to slaughter each other.
Adamant that she would win out in the slaughter and complete herself fully as a curse doll so she could escape from Mother's influence, Sithonia secretly plotted against her sisters. She tried to kill her main adversary, Elsa Featherrun after all of the other sisters were out of the picture, however she was easily defeated, and chose to be killed by her so she could be finally free of her abominable Mother.
Curse Doll (呪い人形): As an imperfect curse doll, Sithonia possessed immense regenerative capabilities giving her a pseudo-immortality. Sithonia was also able to control the shades of the girls who had failed to become curse dolls via her ability, and use them in attack. In addition, she could also transform into and imitate people with exceptional accuracy.