Phantom is the first and the strongest of the Chess no Koma. In the past war, he fought against Danna, killing him and being killed himself, but thanks to Peta's help, he could reborn some years later. He hates human being and all about them (although it could seems, he isn't a human, but a zombie) overall MäR Heaven, that he wants to destroy.
Apparently he seems a quite man, who always smiles, but who hides a dark soul and full of hatred. Even if he's heartless with his enemies, he's always loyal with the other components of the Chess team, so that if they lose their fight in a War Game, he leaves them alive. Is him who command the Chess Pieces during the matches, and all obeys to him both because they respect him and because they know that on the contrary, they will be death.
On the left arm he has a strange bandage, but we don't know what there's under that. He's very attracted by Queen with whom he often talks with and take his orders from. He's immediately impressed by Ginta's power, and because of this he always try to let him fight against his best pieces on the field, hoping that the young boy will become always stronger, up to the day when they'll fight each other.
When he discovers that Ginta is Danna's son, he becomes obsessed with him and waits with anxiety the moment when they'll fight each other, that will arrive the first time in an unofficial match in Kaldea, and the second at the last War Game, with Phantom's defeated. During this match, we'll find out that under that bandage he has an arm composed by differents ÄRMs, of which the most powerful is the one nearest Phantom's real arm. More over, he will die under Alviss's hand, with a key that can freed the boy and Lauren from the curse of the Zombie Tattoo. After the match with Ginta, we'll know that Phantom's mind was manipulated by the Chess no Kouma's King.
We often see that Phantom enjoy himself dressing up as a little boy and going around like that, introducing him as Tom, overall for knowing better and from a nearer point of view, his enemy n.1 Ginta.