Рорі Меркурі

A demigoddess and an apostle of Emroy, the god of darkness, war, violence and death. She is widely known as Rory the Reaper due to her wielding of her halberd as a scythe, slaughtering those who offend Emroy, and those she views are worthy of being punished by death.

Her gothic lolita dress is an outfit for priestesses. In terms of age, she is the third-youngest Apostle of the Twelve Apostles.

(Source: Gate - Thus the JSDF Fought There! Wiki)