Astral

Astral is a mysterious entity in Yu-Gi-Oh! ZEXAL. Some people refer to him as the Dueling Ghost. 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 and unskilled (a fact that annoys Yuma). However, when Yuma uses an unthinkable but effective strategy, such as in his Duel with Shark, his thoughts change to think of Yuma as an interesting Duelist. Astral even learns to use Yuma's lack of skill and obedience, as seen in Yuma's Duel with Professor Ukyo when he tells Yuma what to do the opposite of what he should do so that Yuma disobeys him and makes the correct moves.

Astral has a fear of cats, which he defended by claiming that he hadn't done any observations about them. This is evident when Yuma duels Cathy, even mistakenly believing her to have one of the Numbers in her Deck.

After episode 14, he developed a strong fear towards Kaito, so he always tries to tell Yuma to run from Kaito instead of fighting him, to the point of telling Yuma to forget his friends. He first denied this, but admitted it in episode 17.

Later during the Duel with Jin, Astral overcame his fear and decided to actually fight. After he and Yuma thought about their previous duels, stating they came too far to lose now, Yuma called Astral his friend, restoring his fighting spirit.

Astral doesn't smile much, but for once, he smiled for Yuma recognizing him as his comrade and smiled often at Yuma throughout episode 19 and even cheered him on with his friends and family when he was trying to do his 20-stack challenge.

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.

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

During the Duel with Kaito Tenjo, he found very suspicious that someone besides him and Yuma are looking for the Numbers. He also was surprised that Kaito's Dueling skills were even superior than his, when he was sure Yuma lost and he would die, Kaito cancelled the Duel. He was left shocked at what happened next to Yuma whose pride was severly hurt and even questioned about his Kattobing spirit.

Later during climaxes in the Duel with Jin, Astral overcame his fear and decided to actually fight. After he and Yuma thought about their previous duels, stating they came too far to lose now, Yuma called Astral his friend, and The Emperor's Key started to shine. It resulted in granting him and Yuma a new power, the Chaos Number, Chaos Number 39: Utopia Ray as well as making Astral appear and Yuma's friends able to see him for a moment. Using it, they defeat Jin and take the 2 Numbers cards he was using.

Yuma's friends who were freed in the process, all went to thank Astral instead of Yuma, running right past him, still unable to see him, and thus were shouting at nothing, and Astral didn't pay much attention to it, keeping his cool. Perhaps, he can now only been seen in Augmented Reality.

During the next episode, Astral assists Yuma in trying to locate The Emperor's Key after discovering it missing. He learns much about the origin of the Key and Yuma's father, who had a vision of the Astral World being attacked and the sound of people screaming. A strange figure, much like Astral, gave him the key. Astral is much kinder to Yuma, smiling warmly at him and encouraging him to takle the high jump he attempted at the start of the series.

After safely recovering "Number 96: Black Mist" from a stranger, Tetsuo and Yuma start to fight. When Tetsuo knocks off The Emperor's Key from Yuma, a Black Ooze comes out of Yuma's Deck Case which grabs Yuma and starts taking control of Astral. Before Astral gets completely taken over, he tells Yuma to give "Utopia" to Tetsuo. Afterwards he gets completely possesed and changes from white to pitch-black. Number 96 (In Astral's body) tries to take "Utopia" from Tetsuo, but The Emperor's Key protected him. Tetsuo then challenged Number 96 to a duel for the Number. Number 96 accepts and takes control of Yuma's movements to duel. In his first turn, he Xyz Summons Number 96: Black Mist and starts inflicting huge damage to Tetsuo. Tetsuo however Summons "Utopia" and tries to make a counterattack, but fails in doing so and "Utopia" is destroyed. Yuma then pretends to be under Number 96's control and tells him to destroy Clockwork Explosive while explaining its effect. Number 96 listens to Yuma and destroys Clockwork Explosive. This however was a trick as it allowed Tetsuo to summon "Clockwork Shikigami" as well as resurrect "Utopia" to win. Tetsuo then throws the Emperor's Key back to Yuma and Astral is freed from its control. Astral then absorbs Number 96 again, while Tetsuo returns "Utopia" to Yuma and they both apologize to each other.

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 defeated opponent without direct contact, although it is unknown if this is also linked to a rather psychokinetic ability. So far he has only shown being able to pull out one "Numbers" card at a time, even if the opponent should posses more than one "Numbers". He also has some sort of control over how Numbers behave in battle or can gain access to new Number cards at certain times. For example; after Yuma refuses to sacrifice him during the battle against Jin, Astral recieved a jolt of power from The Emperor's Key and was able to provide Yuma with a new Numbers card. This also made him visible to the others wearing D-Gazers.

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 or when Yuma is losing life points in a duel with an opponent that has a Number.

Trivia

 * Astral's relation with Yuma mirrors Yugi Muto and Yami Yugi's relation in many ways. Like the first series protagonist, Astral is a 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.
 * Astral bears a resemblance to the spiritual entity on the card "Astral Barrier".
 * Astral's observations stopped after their Duel with Kaito which left him quiet and depressed. However, after their Duel with Jin, which restored his and Yuma's confidence, his observations returned.