Astral

Astral is a mysterious entity in Yu-Gi-Oh! ZEXAL. It is said that Astral is from a parallel universe. He is a clear-minded fellow with a cool personality and a Dueling genius. He often clashes and fights with his partner, Yuma Tsukumo. He also tends to call Yuma "Tonma" (Roughly translated to "Chowder head"), much to Yuma's annoyance.

It is said that his memories have scattered in the form of the 99 "Numbers". Furthermore, these Numbers are Special Exceed Monsters that cannot be killed with cards in this world. When 2 or more Numbers confront in a Duel they'll fight each other to consume one another. When they're defeated in a Duel they're absorbed into Astral.

Biography
A new legend began when Astral appeared before Yuma Tsukumo and Ryoga Kamishiro. He comes from a different dimension and somehow he ended up in Yuma's dimension. He lost his memories but all he remembers is that he was looking for a talented duelist. In episode 2 it is revealed that only Yuma can see Astral which makes everyone believe he is a ghost

Manga
Kotori Mizuki considered that he is a ghost. Right when Yuma is about to give up hope against Shark, Astral appears and says to Yuma "Stand up and win!".

Numbers absorbed
1. No. 17 Revise Dragon (Rank 4/Episode 2)