He, Aigami, Sera, and other orphans lived with an abusive man, until Shadi arrived and killed the man. He and the other orphans then began to live with Shadi, until Shadi was murdered by Yami Bakura.
Aigami, Sera and Mani resided with a group of children, on a plateau above the clouds. Aigami decided to leave one day and went with a group of children. Mani also left to keep an eye on him.
The Dark Side of Dimensions
Mani was at the ruins in the Shrine of the Underworld, as they were excavated. He was wearing a cloak and hood, partially covering his face. Some time later, he was seen alongside Sera and Aigami watching from afar as Yugi and his closest friends reminisced about their separate futures. Sera recalled how she and Aigami were young orphans in Egypt and how they had befriend him.
He and Aigami then teleported to the Shrine of the Underworld, where Kaiba and Aigami Dueled. After the Duel, he saw a glowing light in a pit, and found the Millennium Ring there. He then picked up the Ring, and his mind got warped by its evil.
When Aigami was talking to Bakura, Mani arrived, influenced by the Ring, and was about to kill Bakura, until he came back to his senses, and instead knocked Bakura back, telling Aigami to run.
He and Aigami were then transported to another dimension, and he incinerated thanks to the Millennium Ring. After Aigami was defeated by Yugi and Atem, Mani was revived, and he parted ways with Sera and Aigami, on good terms.