Muru Muru

Muru Muru is the servant of Deus Ex Machina and serves as a judge along with him in the Survival Game. She rarely appears in the main storyline, usually serving as comic relief in side-stories in both manga and anime. As the series progresses she reveals herself a major antagonist who plots behind Deus to manipulate the events of the game for her own personal fun. She also appears as an antagonist in Future Diary: Paradox.

Personality
Akin to her appearance Muru Muru is a childish individual who seeks nothing more than to have fun with the Survival Game. She also is quite mischievous and more than in one ocasion has been seen disguising herself as other people (and is actually mistaked to be the real one), to sneak in places for seemingly no reason at all. She's also known to be an avid Manga Reader and it is suggested she reads mostly shoujo manga.

Despite these peculiar quirks, Muru Muru has shown to be in fact a manipulative, cunning, and sneaky invidividual who plots behind Deus and uses the other participants in the way she sees fit to make the game more fun for her, thus indicating she has little if any loyalty towards Deus, although she does respect the game rules and does not use Deus powers for herself.

She also seems to belittle humans, or at the very least non-participants, believing the likes of Aru Akise to be unfit to enter the Cathedral of Casuality.

Abilities
Being Deus servant, MurMur has several superhuman abilities of her own. She is can teleport herself from the Cathedral of Casuality to the real world as she pleases, can teleport with enough speed to evade an attack from Deus as well as teleport others. She can also travel through time, and even show events of another timelines in a cinematic way.

She's also a capable fighter, being able to manipulate a large orb used to easily smash debris or even trap people in an illusion-world, as well as stop a bullet with her bare hands. She's also capable of manipulating memories, either removing or implanting them at will, the latter being apparently a much longer process. Despite all of this, it is seen that her normal child-form is in fact restrained, and when the seal placed on her is broken, she becomes a bigger monstrous version of herself who is much more destructive.

It is suggested that she has powers that rival or are close to Deus himself, as even when Deus does know that she's plotting against him, does not act directly against her, although this could be because of his decaying lifespan, and resorts to mostly restraining her rather than destroy her.

Trivia

 * She's named after the demon MurMur