Yu-Gi-Oh! GX episode 138: "The Darkness Revealed"
Nero is a young boy, one of the residents of a village in the the alternate dimension.
Nero hides from the forces of The Supreme King in a cave, guarded by his elderly grandfather. Nero wants to become a great duelist one day, and wishes to defeat The Supreme King. He practices drawing with a rusted Duel Disk, which doesn't even appear to have any cards in it. He and his grandfather are approached by Jim Crocodile Cook and Axel Brodie, who question if they've seen Jaden Yuki, showing them a photograph of him. They have not, and tell him that if Jaden is a duelist, he has likely be captured by The Supreme King's forces. Nero and his grandfather take Jim and Axel back to their village, where they introduce them to Burgundy, who initially mistakes them for members of the King's Army. Thus, he knocks Jim out. Later, Jim and Axel leave the village to find The Supreme King. They find their trip to his keep a waste of time, finding only Kozaky there. They return to the village in time to see it destroyed as Burgundy urges them to flee. Jim sees Nero's Duel Disk on the ground, and realizes the boy has been killed as well. This is one of the final factors the pushes Jim into challenging the Supreme King.