Emperor's Key

The Emperor's Key (皇の鍵, Ō no Kagi), sometimes shortened to the Key in both versions and also called the Golden Key in the dub, is a pendant belonging to Yuma Tsukumo.

The Emperor's Key is a mysterious artifact given to Yuma by his parents (mother in the manga, father in the anime). In the anime it is revealed that Yuma's father obtained it from someone similar to, if not, Astral himself, and when that occurred, Yuma's father saw the attack occurring in the Astral World.

The Key allows Yuma to bring Astral forth, which is similar to that of when Yugi Muto turns into Yami Yugi. Astral can go into the Key and spend most of his time in a pocket dimension. In case the Key is taken from Yuma or Yuma loses it, Astral will be trapped inside the Key if he is within it. However, that won't be the case as long as he is outside of the Key.



There is a structure in the Key that, according to Astral is some sort of "spaceship". Inside the ship's construction is a puzzle, which is made up of hundreds of gears marked with numbers that react with the "Number" cards that Astral absorbs, making them move and glow. When a "Number" appears on the machine it starts turning on its pieces. Astral assumed that it had to do with the person who is responsible for the loss of his memories. The "Number" cards also appear to lock into the structure and become apart of it, which keeps them safe. The "Numbers" are printed on square pillars that stick out and glow, but if the Key is separated from Yuma's deck then the pillars go back into the structure and the "Numbers" become cards again meaning they are in danger of being taken.

At the beginning of the series, a diabolical door has haunted Yuma in his dreams trying to convince him to open it. The Emperor's Key was also the key to open that door, which released both Astral and the "Numbers"; and to do so, the broken key restored itself. When the Key got separated from Yuma, a voice said that "Astral is immersed in the guidance of time" and that he must obtain the "power of ZEXAL". The voice described it as a power that turns all darkness into light. The Key has power to release the "Number's" "alternate form", "Chaos Number".



The Emperor's Key gives the user some sort of immunity against the Numbers' influence, or at least reduce it. When Number 96: Dark Mist tried to take "Utopia" from Bronk Stone by force, and when Bronk Summoned "Utopia". When Shark had the Key and took control of Kite Tenjo's "Acid Golem". This is possibly due to its connection with Astral, and supported by the fact that Yuma has not been influenced while most others are have "possessed" by the "Numbers" and the number appearing on the user's body. However, the Key was unable to fully suppress the power of a "Chaos Number" when Yuma took control of "Number C32: Shark Drake Vice". Though the "Chaos Number" did not possess him, the connection to it weakened Yuma and surronded him in a dark aura which was eventually electrified, causing him great pain.

The "Numbers" have power inside the Key, as when Astral sent "Number 39: Utopia" off, the Key fired the card out of the Key and into Yuma's Extra Deck.



The original owner of Key, Kazuma Tsukumo, also has power over the Key as well. He mysteriously appeared in the Key and used the power of the 12 collected "Numbers" to break Tres's influence over Yuma, allowing him to regain his "kattobingu". Kazuma later returned to tell a revived Astral that his son is calling him for help.