Natassia (Episode G - Assassin)

Natassia (ナターシャNatasha) is the adopted daughter of Hyōga, she is an amalgam of several dead bodies created by the leader of the Faceless,Wadatsumi  who used her body as a container for his liquid form but also served to deceive his opponents into not attacking.

Past
"Natasia" was created by Wadatsumi as an amalgam of several dead bodies to be used as a container for his liquid form.

Dad?
After the defeat of the leader of the Faceless, Wadatsumi by Aquarius Hyoga with Diamond Dust Hyoga encased the girl's body with Freezing Coffin. Later after the fight she leaves the Freezing Coffin feeling scared and cold with no recollection of what has happened since she has lost her memory. She asks for her papa and Hyoga hugs her stating that he's here. She then asks him what her name is to which he replies Natasha and that he's given her his mother's name.