Mastema is a loyal henchman of the Demon. Long ago, Demon saved her from death and she pledged herself to him. On the day that Demon decided to give up his position as a commander of the Black Wings, he gives Mastema a letter to give to the Heroes. She shows extreme concern, but goes through with it anyway.
After she delivers the letter, she is attacked by Arkarium, who fatally wounds her. She transforms into a cat to sustain her life and tries to find a way to turn back to her true form.
A hundred years later, she meets the Demon in Edelstein and agrees to help him recover his lost powers.
At level 140, there is a quest that involves retrieving a potion at the Temple of Time that temporarily reverts her back to normal. After all the hard work, Mastema attempts to confess her love to the Demon, but turns back into her cat form before she can finish, and the Demon remains oblivious.
- Mastema's gender is based on the gender of Demon; if the player is Male, then Mastema is Female, and vice versa.