Cell Roron

Cell Roron, one of the minions of the Noah Family, is the "Prisoner of the List Cage", keeper of the list of people the Millennium Earl wants killed.

Appearance
Cell Roron is a being who lives in a three dimensional cell within a two dimensional playing card. He is an unusual creature whose body bears a basic humanoid shape but has no defining muscle features. His mask-like face bears a strong resemblance to some of the designs of the Tragedy of the Tragedy Comedy drama masks, and the top of his head curves back like a pointed hat and ends in a ball.

Personality
Cell Roron seems to constantly be a depressed and miserable being; his tone is always dreary and it is easy to make him cry. He also seems to be a bit obsessive compulsive when it comes to erasing names from the inside of his cage, going so far as to raise his voice to Tyki when the Noah refuses to believe that Allen's name won't erase from the walls. He shed a tear immediately after his argument with Tyki, though, showing he is also easy to upset.

Order in Crisis arc
Cell Roron, though not seen directly, is first introduced when Tyki Mikk returns to the Noah Family hideout and receives his from the Earl orders to 'delete' people on a 'list', whereupon the Earl hands Tyki Cell Roron's card.

Suman Dark's Fallen arc
After Tyki kills Suman Dark, he pulls out Cell Roron's card to confirm whether or not Allen Walker is his target, to which Cell Roron positively identifies Allen for 'deletion.'

Later, when Tyki has arrived in Edo, Cell Roron informs Tyki that Allen's name will not wash off of the wall of his cell. Tyki whacks Cell Roron's card with a koi and demands that he scrub harder, making Cell Roron cry out that Allen isn't dead. When Tyki stares at him in shock, Cell Roron sheds a tear and sniffles.

Noah's Ark arc
When the Exorcist group reaches the top of the tower in the middle of the town within Noah's Ark and meet up with Tyki and Road Kamelot, Cell Roron is seen hovering next to Tyki's head, muttering Allen's name obsessively. He stays beside Tyki for the duration of Tyki's talk with Allen, and when Allen and Tyki start fighting, he disappears.

Powers and Abilities
Identification: Cell Roron can positively identify those who are on the list within his cell to be 'deleted,', even if he has never met them before.

Death Perception: After a person within the List Cage has been killed, Cell Roron will attempt to wash their name from his cell using a mop. If the name does not erase, he knows that the person is not dead, just as, conversely, if it does erase, he knows that they have passed on.

Trivia

 * It is unknown if Cell Roron is a golem, a magical being or else.