Maria is a Demon who became trapped in a tower at some unknown point in time. She eventually became bored out of her mind there, and resolved to make her way to the human world, however due to the fact that she is unable to operate the device that can transport her there alone, she traps the protagonist and his friends in her tower and tricks them into collecting the seven orbs for her to operate the device.
She initially appears to them as a lost little girl being attacked by Demons, when she is saved by the protagonist. She joins them on their journey up the 100-floor tower, eventually revealing to them that she is malevolent on the 99th floor. Once they've reached the top, she reveals her true intentions, and that she used the group to enter the human world and destroy it.
She engages in battle with the group, revealing her true form as the Demon known as The Destroyer, however she is destroyed, and in her final moments she calls out that all she wanted to do was go to the human world.