The Door The Door ( 扉 " Tobira " ) is a diabolical gateway that appears in the " Yu - Gi - Oh ! ZEXAL " series . There are two doors - one of which held Astral and the " Number s " and is unlocked by the Emperor ' s Key , and one which held " CXyz " which is unlocked with the Barian Emblem . The Door is voiced by Inoue Kazuhiko ( Japanese ) and Marc Thompson ( English dub ) . Astral ' s Door . Anime . When Kazuma Tsukumo obtained the Emperor ' s Key , he gave it to his son , Yuma Tsukumo , who always wore it as it reminded him of his parents . Shortly afterwards , the door started haunting Yuma in his dreams , causing him to have the same nightmare almost every night . In these dreams , Yuma meets the door and a voice says ; " Whoever opens this door will obtain a new power , but in exchange will lose what they appreciate the most , " but Yuma always wakes up before he can open it . The dub replaces the second half of the statement with " but know that with such a reward comes great risk " . The voice then questions if Yuma has the courage to release the ability to discern the humans who are possessed by the " Number s " . During Yuma ' s Duel against Shark , the Emperor ' s Key , which was broken at that time , responded to Yuma and took him to the door again , repairing itself in the process . The door once again told Yuma to open it , which he did using the Emperor ' s Key . When it was opened , Astral was released , but some shock caused Astral ' s memories to break into 100 blank card s . Astral was then fused with Yuma . While Yuma was being combined with Astral , he saw the one - hundred blank " Numbers " around him in a sphere . The sphere quickly broke and the " Numbers " were all scattered except for , which Astral kept . When Yuma returned to reality , he thought it was just a dream , but seeing the Emperor ' s Key repaired convinced him otherwise . Shortly afterwards , he meets Astral . At a later point , Yuma and Astral mentioned The Door when discussing the Emperor ' s Key . Later , it appears once again in front of Yuma and reminded him of their covenant : The Door gave him a new power , but in exchange Yuma will forsake his most precious belonging . Then it says that someone is interfering with the deal , and gives Yuma the power of ZEXAL so that he can defeat Kite . It was revealed that beyond the other side of the door is an entrance to the dimension that is inside the Emperor ' s Key . Sometime after the World Duel Carnival , Yuma dreamed about the door once again , and it repeated the same message . However , this time the voice told him that he will be losing that which is important to him soon . After the duel against Girag , Astral tries to gather memories of the " Numbers " he had already collected , but still couldn ' t reach . Then he is transported to the door , who tells Astral it was going to test him , in order to obtain the true memories of the " Numbers " , and says that at that time , everything would start to move . The door then vanished , and the Shadow Giant appeared in front of Astral , in order to test him through a Duel . After Yuma , who is brought to inside the Key , and Astral defeat the Shadow Giant , the door appears again in front of them , with Yuma recognizing that the door from his dreams . The door then tells Astral to remember his mission , showing him and Yuma a vision , which makes Astral remember the Numeron Code . When Yuma Dueled against Nash , Yuma realized that with the power that he obtained with Astral , the trade - off would be to lose who he truly was , his idealistic ability to connect with others , which he ultimately defied . During his Duel with Astral , the latter used " The Door of Destiny " card , which transported him and Yuma in front of it . Yuma reflected how this was where he and Astral first met . Recalling the Door ' s words , Yuma came to realize what he will have to lose his most important thing - Astral . Although conflicted , Yuma had come to accept this at Astral ' s urging . Manga . After Mirai Tsukumo gave the key to Yuma , he had dreams about it for years . The Door says that the one who opens this door will receive great power , but as compensation will lose something important to them . During his Duel with Shark , Yuma finally opened the door , leading him to release the " Number s " and meet Astral . Barian Gate . Five years before the events of World Duel Carnival , Dr . Faker conducted research about finding the doorway to the other dimension , assisted by Byron Arclight . With Kazuma Tsukumo ' s help , they located the remaining two of twenty - three odd phenomenons in the world , which allowed them to deduce the location of the door . After finding the door , Faker betrayed both Byron and Kazuma , sacrificing them to enter the Barian World . On the other side of the door , Faker encountered the Barian Emperor Vector , who agreed to heal Faker ' s son , Hart Tenjo in exchange for Faker destroying the Astral World . Vector stabilized Hart ' s life with his powers as Faker worked to complete the Sphere Field Cannon and collect the " Number s " . If Faker did not succeed , Vector would take Hart for himself . When a duelist performs a Chaos Xyz Evolution by Rank - Up with their " Numbers " using a Barian World ' s " Rank - Up - Magic " card , the Barian Gate appears , with their " Chaos Numbers " coming from inside it . The monsters are of Barian origin , and belong to ( because of the energy inside the monsters ) or from the Barian World .