OVA
Description
Mur Mur assists the deity governing the Survival Game across realities, her origins rooted in Germanic folklore where such beings served higher powers with mystical abilities, not inherently evil. Initially seeming minor, she manipulates events for amusement, progressively revealing antagonistic motives by working against her master.

She appears as a diminutive humanoid with dark skin, lavender hair, and purple eyes. Her attire features a pink turtleneck vest, white briefs, large shoes, and flared leggings, with silver bracelets limiting her powers. After her master's demise, her look shifts to a light blue vest, full pants, a tattered cape, a small crown, and an X-shaped bandage hiding a numeral "1" marking her origin world.

Her personality blends childish mischief with calculated cunning. She enjoys disguising herself, reading shoujo manga, and treating the deadly game as entertainment. Despite her playful facade, she displays manipulative tendencies, showing little loyalty to her master and belittling interfering humans. Her relationship with her master is complex, occasionally resembling a parent-child dynamic in bonus segments, complicated by her role as an impostor from another world.

Her abilities encompass teleportation across dimensions, time manipulation, memory alteration, and reviving the dead by rewinding personal timelines. Combat skills include energy projection, illusion creation, and environmental manipulation within specific realms. Removing her bracelets unleashes a monstrous form with enhanced strength and speed, draining significant energy. Her powers approach her master's level, explaining his reluctance to confront her.

In the first world's timeline, she supports the original Survival Game but later sides with victor Yuno Gasai. After Yuno fails to resurrect her loved one, Mur Mur suggests time travel, inadvertently stranding them in a parallel world. She facilitates Yuno's takeover of her alternate self's life and aids her entry into the second game. In the second world, she imprisons her local counterpart, poses as an imaginary friend, and secretly manipulates events to favor Yuno. She alters timelines by revealing critical information to participants, hastening conflicts for her amusement. When her master weakens, she declares herself interim deity and attempts to eliminate Yukiteru Amano before being thwarted.

In the Redial narrative set in the third world, a distinct Mur Mur exists where the Survival Game never occurred. This iteration blocks Yuno Gasai from reaching the divine realm for rule violations but is overpowered by Minene Uryuu, allowing Yuno to proceed. Later, the first world's Mur Mur reappears, transferring the original Yuno's memories to her third-world counterpart, enabling Yuno's reunion with Yukiteru Amano after millennia.