Interdimensional War

The Interdimensional War is a prolonged engagement between the Astral World and the Barian World, with Earth caught right in the middle. It ultimately serves as the main conflict of Yu-Gi-Oh! ZEXAL. The Numeron Code is the ultimate objective of both sides as it decides the victor and fate of both worlds and Earth.

Astral vs Don Thousand
It is said that the emissary of Astral World, Astral fought against the god of the Barian World, Don Thousand. Astral ultimately emerged victorious, sealing Thousand in the Sea of Ill Intent, but brought chaos to the Earth in the process, according to Jinlong. Also,during the battle, a shard of Thousand's malice was trapped inside Astral. It eventually developed into the form of Number 96, which was the embodiment of the power of a "Forbidden Number".

Past Lives
It is revealed that before becoming Barians, the Seven Barian Emperors were human once in their past lives, with each of their past being connected to each ruin the Legendary Numbers were hidden in, along with the numbers themselves and their protectors.

The Missing Barian Emperors
The leaders of the Barian Emperors, Nasch and Merag, went missing at some point. According to Thousand, Vector is the one responsible for their disappearances, as he murdered them.

Prelude
Not much is known on how the war between the two dimensions really started, with the only clue being said from Durbe and Mizael that one cannot exist while the other survives.

Barian World
Due to the fact that the residents of the Barian and Astral Worlds are high-energy beings that cannot interact with each other and being unable to take the Number themselves, Barian Emperors Durbe and Vector enlisted humans to do it for them, serving as their benefactors.

Dr. Faker Faker was forced than recruited, as Vector threatened to hurt his child, Hart, unless Faker brought Vector "Numbers", which would appease him.

Hart Tenjo Like his Father, Hart became a forced pawn of Vector from receiving his Barian energy, which not only gave him powers, but a few harmful side effects as well. From this he would be forced to use his powers to aid Faker in destroying the Astral World.

Vetrix Family While Vetrix wandered the Barian world, Durbe released him and sent him back on Earth. Vetrix, thankful of this act, aided Durbe and was tasked to bring the "Numbers" and Durbe gave him and his sons power in the form of crests, though Vetrix only wanted one thing - revenge on Dr. Faker.

Mr. Heartland

Astral World
The Astral World, through the Barians' recruitment process and Dr. Faker's offering, would gain the assistance of two beings who believe in possibilities and posses incredible tenacity: the great adventurer Kazuma Tsukumo and by extension his youngest child, Yuma Tsukumo. Kazuma Tsukumo Kazuma found the Astral World for a short moment before going back to Earth with a golden relic given to him by someone looked like Astral or Astral himself, which he gave to Yuma. He and his wife began to believe that through dueling, Yuma would eventually have to bear a great and dangerous destiny. Thanks to Dr. Faker's betrayal, Kazuma was sent into Astral World again and was trapped within it. From here, he sent Astral to Earth to help Yuma.

Yuma Tsukumo Since receiving the golden key, Yuma began to dream about a door. One day, during a duel with Shark, Yuma unlocked the Door, which led to meeting Astral, with the unintended effect of having his memories scattered into 99 "Number" cards. By teaming up with Astral, Yuma hunts down the "Numbers" through many trials and adversity, ultimately becoming a key player in the fight against the Barians.

Current Events
Before WDC Yuma is surprised by being told of a ship within his key by Astral. Astral also states that only by gathering the "Numbers" will they solve its mysteries.

Meanwhile, Kite began to grow more concerned for Hart as his physical and mental well-being continued to worsened from using his powers, but Hart insisted on continuing since he believed he was helping the world, while Mr.Heartland told Kite to focus on gathering "Numbers" if Hart is to be healed. Kite suspected that Dr.Faker was hiding the truth behind the mystery of the "Numbers", so he had Orbital 7 research their origins, which lead to Kite seeking the Emperor's Key Yuma wears which their connected to.

World Duel Carnival
In an effort to help Kite Tenjo gather "Numbers" more quickly, Dr. Faker and Mr. Heartland devised a very clever plan: Holding a Duel Tournament called the World Duel Carnival. Duelists from all over the World will come to Heartland City to wage heated duels, all to claim the Title "Duel Champion". Thanks to Kite, Yuma was allowed to be in the tournament when he failed to sign up in time, though this was initially so that Kite would have another chance to face Astral. During the tournament, Yuma and Astral faced off against not only Kite and Shark but other strong duelists as well, Number holders or otherwise, including those of a more mysterious, powerful and sinister group known as the Vetrix Family.

WDC Finals
Battle of the Duel Coaster

Battle of Heartland Duel Tower

Battle against Vector,the Barian manipulator

Attack of the Barians
Due to Vector's failures with his pawns and his presumed death, the Seven Barian Emperors decided to take a more direct approach in gaining the "Numbers" and dealing with the users of Zexal.

The Barian Pawn Threat At Durbe's request, Gilag was the first to head to Earth to deal with Yuma and Astral. To this end, he started to use brainwashed pawns, starting with Fuma and his gang of thugs. Meanwhile Yuma had a vision that someone has come to take his most precious something from him.

Astral's True Mission Revealed

Vector Returns Despite losing to Yuma and Astral yet again, Vector tries to kidnap them. At the last moment, however, Rei steps in and gets kidnapped instead. Before disappearing with Rei, Vector gives Astral the "Master Key Beetle" Number card, saying it will open the door to their final faceoff(and Vector's perfect trap for Yuma and Astral).

Battle of Sargasso With "Number 66: Master Key Beetle" in hand, Astral is able to activate the Different Dimension Airship inside the Emperor's Key. Yuma decides to stage a rescue mission to Barian World to save Rei. He and Astral sets out, with Kite, Shark, Rio, Orbital 7 and the members of the Super Secret Number Cards Investigation Club in tow. As they make their way to Barian World, they come under attack by an army of monsters. Yuma, Shark, Kite, Rio and Bronk went outside the ship and use their respective ace monsters to hold them off, until they are all sucked into a black hole that sends them to "Sargasso", where Vector, Durbe and Mizael awaits.

Search for the Legendary Numbers
After Vector's plan at Sargasso failed, his hatred for Yuma and Astral reached dangerous new heights. To that end he sought out the power of Don Thousand.

Once Thousand was revived, Vector offered his life to him in exchange for the power to defeat Yuma and Astral. Thousand then explained that in order to be fully revived, he would need the power of seven sealed "Legendary Numbers" hidden on Earth. Vector agreed with Thousand and they merged, giving Vector new powers and fully healing him. While at first having trouble with Durbe and Mizael due to his failed plan at "Sargasso" making Yuma and Astral stronger, he manage to convinced them to join him in the search for the Legendary "Numbers" with the help of Mr. Heartland, revived as a fly, due to the knowledge he gained from his time with Faker, along with mentioning the possibility of finding the missing Barian Emperors, Nasch and Merag as well. After the two left to start the search, Vector used his new powers to accelerate the healing of Gilag and Alit.

Truths that Connect Three Worlds Number 96's Last Stand and Astral's Sacrifice After mastering his new powers of Chaos, Number 96 was determined to not only defeat Yuma and Astral, but also destroy Astral World, Barian World and Earth as well. After launching an attack on the worlds, he summoned Yuma and Astral, along with Shark, Kite and Tori to his location into settle things with the Zexal pair once and for all. Despite the advantages he held from his "Chaos Field" Spell Card, one of which allowed him to steal two of Yuma's "Numbers" and have them Ranked-Up, Number 96 was ultimately defeated by the duo through the power of ZEXAL II. After his defeat, Number 96 tried one last attack to kill Yuma and Astral. Astral took the blow and absorbed him, ending Number 96's threat once and for all. Before disappearing with the golden key, Astral thanked Yuma for everything and left the duty of gaining and protecting the "Numbers" to him.

Don Thousand's Master Plan unveiled With Astral gone and his "Numbers" in Yuma's care, along with the return of his missing piece of power from the shard that was within Astral, Thousand decided to get back to working on his master plan. After showing Vector to his old palace, he let Vector in on his goal. First he granted Vector four "Numbers", but told him that he would have to wait a while to use them against Yuma and showed him a device crucial to the plan. Using this device, Thousand would merge Earth and Barian World together, thereby allowing the malice of the human world to equal the malice of the Barian World, giving him all the power he needed to destroy Astral World. For this to work, he would have to make more of the devices, which was possible thanks to the power he regained from a shard that was inside Astral, the "Forbidden" Number 96: Dark Mist, thus Vector finally understood why Don considered him important. He then fused to Vector through the throne in the palace and after returning Mr. Heartland to his human form, gave him and the other members of the Fearsome Four of the Dark Dueling World the four "Numbers" in order to take the other "Numbers" from Yuma and his allies.

Fighting alongside the Arclight Brothers

Journey to Astral World