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 "Toma" (Roughly translated to "Chowder head"), much to Yuma's annoyance.

It is said that his memories are scattered in the form of the 100 "Numbers". Furthermore, these "Numbers" are Special Xyz Monsters that cannot be killed with cards in this world. When 2 or more "Numbers" confront in a Duel, they will fight each other to consume one another. When their owners are defeated in a Duel, the cards are absorbed into Astral.

Personality
His personality is rather ambiguous, he is very intelligent and level-headed when it comes to Duels and even in disastrous situations (often caused by Yuma's mistakes) he does not seem to lose his cool and can think of a strategy. Outside this he is, arguably because of his memory loss and sudden arrival to another world, curious to the point of naivety, for matters as simple as eating, going to the bathroom, or believing that TV shows are real. His naivety would go to such extent so as to ask Yuma why "he needs to be alone" when Yuma's in the bathroom, to which he replies by saying that he would "die" otherwise, a thing that Astral took literally. However, this is more likely because Astral doesn't know anything about Yuma's world. When he "discovers" things, he has an habit of saying "observation number one, two, three" and then speak the result of his analysis. He has also ambiguous thoughts regarding Yuma, for the most part he thinks of him and his Dueling skills as unrefined, unskilled, etc. A fact that annoys Yuma, in the other hand when Yuma uses an unthinkable but effective strategy, such as in his Duel with Shark, his thoughts about Yuma changed saying that he was indeed an interesting Duelist. Astral even learns to use Yuma's weak skill and lack of obedience as seen in Yuma's Duel with Professor Ukyo when he tells Yuma what to do the wrong moves so that Yuma disobeys him and makes the correct moves.

Astral has a fear of cats, to which he defends claiming that he hadn't done any observations about them, that is evident when Yuma Duels Cathy, even believing her to have one of the Numbers in her Deck although at the end of the Duel he is then mistaken.

Anime
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. At the end of Episode 8, it is mentioned of Astral's birth, and that he may have had a mother. And also he was given the mission to protect the world, possibly meaning he was created solely for this task. In episode 10, Astral surmises from within The Emperor's Key that it might have been made intentional by someone to scatter his memories.

As Astral absorbs the power of the "Numbers", bits and pieces of his memories start to return, most of them incomplete. Upon absorbing "Number 83: Galaxy Queen", he sees a vision of his birth. Recently, when he absorbed "Number 61: Volcasaurus" and "Number 19: Freezerdon", he had a small glimpse of the fate of his world, which was apparently destroyed by some sort of disaster. Possibly, he is the sole survivor of his planet, and whatever destroyed it may have caused him to lose his memories.

In episode 13, Dr. Faker stated that a messenger from the Astral world would appear together with the Numbers, obviously referring to Astral.

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!".

Abilities
Astral is a Duelist of another universe, and has only been seen alongside Yuma. However, even with his loss of memory it has been shown that Astral is indeed a very skilled Duelist, a fact he himself recognizes despite his amnesia, and further demonstrated in how he has advised Yuma on his play, only for him to play the opposite of what Astral dictates and end with rather disastrous results. He shares his information on the "Numbers" with Yuma. He is capable of somehow manipulating the "Numbers" cards, this is seen in two ways, one is that without Astral present Yuma is unable to play any "Numbers" for they do not appear on his Extra Deck, and the second is that he can instantly pull a "Numbers" card out of a defeating opponent without direct contact, although it is unknown if this is also linked to a rather psychokinetic ability. He's also capable of flight as he is always seen floating, and seems to not rely on things such as food to live, however he needs his current partner to have "Numbers" and will start dying if those "Numbers" are taken away as seen in episode 6.

Trivia

 * Astral's relation with Yuma mirrors Yugi Muto and Yami Yugi's relation in many ways. Like the first series protagonist, Astral is spiritual being summoned forth from an ancient artifact that only his partner can see. Also like Yami Yugi, Astral is on a quest to regain his lost memories. In contrast, the two do not get along very well, though their relationship improves throughout the series, also,Yuma is fully aware of Astral's existence since the beginning.
 * Astral's name possibly comes from the term astral projection, the ability to send one's soul to a location somewhere away from the body, similar to Astral's spirit-like form.