Rory Mercury, widely known as Rory the Reaper, is a 961-year-old demigoddess and Apostle of Emroy, the god of darkness, war, violence, and death. She comes from the Special Region, a world filled with magic, monsters, kingdoms, and various gods.

Despite her extraordinary age, Rory possesses the physical appearance of a young girl, having stopped aging when she became an Apostle. She has long, flowing black hair, striking crimson-red eyes, pale skin, and a petite figure. She wears an elaborate black Gothic Lolita-style priestess dress decorated with red ribbons, frills, and black stockings. Her appearance is deceptively innocent compared to her terrifying reputation.

Rory is known throughout the Special Region as the Reaper because of her incredible combat abilities and her position as Emroy's chosen Apostle. She carries an enormous purple-black halberd, a divine weapon that she can wield effortlessly despite its tremendous weight.

As an Apostle, Rory possesses immortality, supernatural strength, incredible speed, heightened senses, and extraordinary regenerative abilities. She can survive injuries that would instantly kill an ordinary person. Her combat experience spans centuries, making her one of the most dangerous individuals in the Special Region.

Rory's duties involve serving Emroy and carrying out the will of her god. She views death and violence differently from ordinary humans, considering them natural aspects of existence rather than inherently evil acts.

She eventually encounters the Japanese Self-Defense Forces after the Gate opens between Earth and the Special Region. She becomes particularly interested in Youji Itami, a Japanese officer whose personality and behavior intrigue her.

Despite her divine status and terrifying reputation, Rory enjoys ordinary social interactions, teasing people, making jokes, drinking alcohol, and accompanying interesting individuals on their adventures.