Ruin

""I'm Unruin-Immortal, you see. None of you negators unloved by God will be able to ruin my dreams.""

Ruin is a negator, self-proclaimed to be loved by God.

He's a known Regulator and has been named by Seal, the King of Negators.

Personality
Ruin is sadistic and mentally unstable, cheerfully slaughtering hundreds of people to make friends with the newly added UMA Ghost, and outright holds humanity in contempt as the "rules" they impose on themselves disgust him. He is a follower of God, and believes he is loved by him, to the point that he has Blood undo the parasol protecting him from the sunlight that harms his skin, believing it to hold "meaning", as the 101 Master Rules hold no errors. Naturally, any affronts to this belief enrages him greatly, such as when Billy points out that his "Unruin" is actually a weaker version of Undead.

Ragnarok Arc
He first appears by stabbing Fuuko through the chest, stating that she isn't allowed to kill Undead. After Andy slices him in retaliation, he regenerates and flees, stating that the Negators will be unable to ruin his dreams. He is then shown to have killed dozens of people to get the newly created UMA Ghost's attention, asking it to eat Fuuko's soul later. When Andy tries slicing him to ribbons, he just says to give up on Fuuko before leaving with Ghost. He later shows up again when the Earth enters Ragnarok, bathing in the sunlight despite it burning him as a sign of his fanatical love to God and the rules they impose.

He then goes on a killing spree, killing hundreds of thousands of people as their corpses wear smiles. He then makes base at a castle at Lucy's village, where a number of UMAs move to. As a result of Andy killing the UMAs in the way to reach Ruin, Seal is imposed as a punishment. Seal then defeats Andy and Lucy and enters Ruin's base as he kills another man, calling him "The King of Negators". Ruin states they, as Regulators, are charged with the mission of preparing for God's arrival, and then warns Seal about underestimating Andy, which proves true as with Lucy's help, he (and the UMAs Seal sealed up) are able to use astral projection to escape confinement. While pinned, Andy asks Ruin where Fuuko and Ghost are, which Ruin reveals that Ghost is "making friends". When Lucy tries to reason with Ruin by saying he should have family, only for the Regulator to rebuke that human rules are disgusting and that he has no family, because he was "birthed" by God. Just before he can attack Lucy's soul, Rip comes in and tears his arm off with his Blade Runner before freeing Andy from Seal. Just before they can fight, his scheme with Ghost and Nico pays off, with Nico betraying the Union and destroying all the UMAs that where keeping Ragnarok at bay. He and Seal then leave, planning to usher God at the Union base.

Ruin and Seal assault the Union base in an effort to destroy the Roundtable and prevent another loop, with Nico helping them under the promise of being reunited with his wife thanks to Ghost. After Ghost is destroyed and Fuuko is revived, Ruin tries to kill Fuuko again, only to be stopped by Tatiana, who holds him off so Fuuko can loop. When she is about to be killed by Ruin, Billy returns and reveals his true Negation ability Unfair to fight Ruin to a standstill, even claiming his Unruin by calling him an inferior version to Undead, allowing Fuuko and Andy to reach the Roundtable and begin the looping process.

He is last seen laughing manically along with Apocalypse as Sun appears to end the world.

Union Arc
He is mentioned as one of the Negators Fuuko wants to save in her plan to create a new Union.

Powers & Abilities
Unruin: He manages to get unscathed from any wounds he receives by nullifying the damage of attacks aimed at him. However, even though he is immune to damage, he cannot deny his death during the loop.

Shadow Portal: After taming Shadow, Ruin gained the power to appear and disappear within the shadows.

Blood Manipulation: After taming Blood, Ruin gained the power to manipulate blood.
 * Blood Wings: Through Blood's power, he can create a pair of blood wings that allow him to fly freely in the air.
 * Blood Clones: Through Blood's power, he can create clones made of his own blood to fight alongside him.

High Pain Tolerance: Ruin demonstrated a high resistance to pain, showing no reaction of discomfort when he was cut in half by Andy or when he was decapitated by Juiz, keeping his smile all the time.

Stealth Master: Ruin proved to be very stealthy when he attacked Fuuko from behind with Andy and the other negators only realizing his presence after he attacked her.