Greta is the adopted human daughter of Yuri Shibuya and Wolfram von Bielefeld. Unknown to herself, she is a princess of the fallen kingdom of Zoracca. Her mother, the Queen of Zoracca, sent her to be raised by her uncle, the King of Svelera, before the kingdom fell. At first Greta tried to kill Yuri by posing as his illegitimate daughter because her uncaring foster parents hated the Maoh and she believed she could earn their love by assassinating him. Not much later Yuri forgives and adopts her. Wolfram follows suit, reasoning that as Yuri's fiancé he is also Greta's parent.

Greta met and befriended Hube while he was imprisoned in her adoptive parent's castle and later helped him to escape.

(Source: Wikipedia)