Don Arlelelle Eruca Fulgrouche (ドン・アルルエル・エルカ・フルグルシュ, Don Arurueru Eruka Furugurushu) is a beyondian and one of the leading bosses of the alterworld. He is big fan of the Prosfair game.
A bulbous insect-like beyondian with claw like limbs, all wrapped in a black cape. Underneath the cape is his massive brain, surrounded by all the smaller brains he has taken from opponents who could not endure a prosfair game against him.
Considered one of the most influential & mysterious Mob bosses in the Beyond, very little is known about him, save that he is an avid Pross-Fair player & is willing to offer favors to anyone who can 'entertain' him for a set period of time in proportion to the magnitude of the request.
Despite his skill, he is not above using psychological tactics & hostages in order to control his opponents, such as arranging for Klaus to be present for Ulchelko's match, knowing he'd offer himself to save the chessmaster, & informing the Libra Leader of Ulchelko's addendum that the Don kill him & K.K to keep his presence a secret hoping it would break Klaus's will at the last second.
Despite the dirty tactics he used in their match, he truly does consider Klaus something of a friend.
Don Arlelelle is first seen when Klaus & K.K arrive at his mansion, deep within the beyond, in order to obtain information on the distribution of the drug, Angel Scale.
However, the Don had set things up purposefully so that Chess Grandmaster Ulchelko would challenge him first, knowing the chessmaster seeking Nuclear weapons for his country would add the addendum that the Don kill Klaus & K.K to keep his presence a secret. The extra hour added is Ulchelko's undoing, as he is just two minutes away from the time limit when disaster strikes.
Per Klaus' prediction, Ulchelko foolishly attempts a checkmate and & is soundly defeated by Arlelelle's counter attack, who then attempts to remove his brain. Klaus intercedes with physical force, as Arlelelle predicted, and the two engage in a 99 hour (the maximum time limit) game of Pross-Fair, now for both the knowledge of the distribution routes & for Ulchelko's release.
During the game, Arlelelle casually reveals Ulchelko's addendum to Klaus with the intent of breaking his will. The plan backfires & Klaus manages to survive the time limit. The Don keeps his side of the bargain, and gives Klaus all existing information on the distribution of Angel's Scale, allowing them to wipe out the drugs presence in Hellsalem's lot in a single day. Ulchelko survives but is horribly crippled from his time playing the game, returning to his home country.
Very little is known about Don Arlelelle, though his power & influence within the beyond is said to border on divine. This is evidenced by the special room he prepared in order to play prosfair, which diverts the law of space time.
He is incredibly intelligent and incredibly resilient with a quick and almost robotic way of playing Prosfair. He is able to play multiple games of Prosfair (A game so complex it can kill unprepared players through strokes and aneurysms) simultaneously against his captive brains.
He is effectively immortal, though his exact life span is unknown. It is at least longer than 1200 years, as according to Ulchenko that was how long the Don has been playing Prosfair.
There are hints in the manga that he is one of the occasionally mentioned Divines, a mysterious and poorly understood class of Beyondian. If true, it would explain his ability to fulfill the seemingly impossible wishes requested of him by opponents.