The Devil Arm is the left arm of the Duel Spirit Yubel after she was launched into space by a young Jaden, when her body disintegrated upon reentry. It was then found by Thelonious Viper on one of his expeditions. It has the ability to see the dark thoughts of any person's mind and can form into a Duel Disk. It also contained the lingering consciousness of Yubel upon her return, in which she required energy drawn from Bio-Bands to return to her true form.