"Let the Duels Begin!", known as "Opening! World Duel Carnival" in the Japanese version, is the twenty-sixth episode of the Yu-Gi-Oh! ZEXAL anime. It first aired in Japan on October 10, 2011, and aired in the United States on August 25, 2012.
The World Duel Carnival, where Duelists from around the world will wage heated battles, is swiftly approaching. Yuma, seeking to fulfill his dream of becoming "Duel Champion", excitedly rushes to the tournament. But what will Yuma do when he has no Heart Pieces, which serve as the proof of participation for the WDC? Meanwhile, Mr. Heartland and Kite make their preparations to gather the Numbers that are likely to assemble before them in this tournament.
This episode also marks the change of the card backing used by the characters.
Yuma Tsukumo waits for confirmation of being registered in the World Duel Carnival since the morning, Yuma asks what is taking him so long, Astral asks who is taking so long, then he sees a deliverer passing by and ask if he has any mail for him. The deliverer checks and double check and reveals that there is no mail for Yuma, which upsets him.
At school, Bronk hugs Caswell, much to the latter's chagrin. Tori ask why Bronk is happy and he says it's because the World Duel Carnival is starting and Caswell reveals that the winner will get a free passport to Heartland City. Flip then tells everyone that the winner also gets 1 wish granted from Mr. Heartland which he says he knows what he will wish and reveals that he will wish for a hundred more wishes, then Cathy says she wishes for a date with Yuma. Flip then talks about Heart Pieces which he, Bronk, Caswell, and Cathy got from the mail. Tori says everyone is competing only to find out that Yuma isn't as he is standing upset, Caswell asks if it came which Yuma says no and cries. Astral feels embarrassed and reminds Yuma that he is invisible. Caswell asks Yuma if he filled up an application for entry. Yuma say's he thought it's just a cool looking picture which Bronk says it's a picture showing him how to apply. Astral says at least Yuma doesn't embarrass himself. Yuma typed in his name and address and enters, but the bad news is registration is closed. Yuma freaks out with a pose similar to the figure in The Scream, he starts to run around, looking for Heart Pieces and runs into Shark.
Yuma asks Shark if he is entering the World Duel Carnival, but Shark isn't interested in entering such a big stage anymore. As Shark leaves, a "Mirror Force" card gets thrown at him. It turns out that his opponent that he faced in the National Tournament, named "Quattro", threw it at him. Quattro thinks it could be useful for Shark to use in the World Duel Carnival then Shark says he isn't competing, so Quattro tells Shark about what happened during the "incident" in the National Tournament: Quattro purposely had his Deck set up so that Shark could see it. Shark wants to Duel, but Quattro says that he has to do it in the tournament and throws a Heart Piece.
Next, Vetrix is watching multiple cartoons at once. Quattro enters telling Vetrix that he has made Shark enter the World Duel Carnival, and asks Vetrix why he is interested in him. Vetrix tells him they need him after collecting all the "Numbers", and Quattro says that he is glad that he can drag Shark into the underworld again (in the dub he says he can put Shark through the ringer again) and laughs evilly.
Meanwhile, Yuma goes to the Heartland office in order to receive heart pieces, and tells the lady in the door's monitor that he will die if he cannot Duel, and pretends to be dying, only to be ignored much to Yuma's dismay and yells loudly, Caswell then says that he should give him points for perseverance. Elsewhere, many of the Duelists entering the World Duel Carnival are shown arriving to the Heartland, while in the main Headquarters of Heartland, Mr. Heartland, Dextra, and Nistro are checking on the Duelists arriving in Heartland. Nistro is excited about the WDC, and Dextra tells him that their job is to watch over the World Duel Carnival.
Kite Tenjo enters the room and asks Mr. Heartland why he was called, and Mr. Heartland tells Kite that he wanted him to see the scenes where Duelists are arriving and tells him that there should be many Duelists that have "Numbers" cards, and that the WDC should involve him collecting the "Numbers" cards, but tells Kite to be careful since many powerful Duelists have arrived. Then Nistro tells Kite that if he is scared, Nistro himself can go collect the "Numbers" instead of Kite. Kite tells Nistro that no one is an enemy of his. Nistro then says Kite is such a good hearted person with a funny face. Dextra tells Nistro to stop, then suddenly on the monitor a worker for Mr. Heartland tells him that there is a boy whose registration was late at the entrance, so Mr. Heartland tells him to send him away, however the worker says the boy claims he won't leave until he gets a heart piece. It is then shown that the boy is Yuma who is holding onto the workers' legs and refusing to leave until he gets a Heart Piece (in the dub, he offers his entire life savings for a Heart Piece which he says is about 75¢). Kite immediately recognizes Yuma. Mr. Heartland again tells the worker to send him away, but before the worker does so Kite tells Mr. Heartland to let the boy have the right to participate, where he asks Kite if he knows the boy, where Kite says no, but that he has the possibility of having "Numbers". Mr. Heartland asks Kite if he is hiding something from him, and that the other day when the building where Kite and Orbital exploded, where Kite just tells him that the machines in there malfunctioned and that there shouldn't be problems if he collects all the "Numbers", telling Mr. Heartland that he has no need to report every single thing to him. Mr. Heartland agrees with him and Kite goes away.
While Kite is heading out, Orbital asks him if he isn't going to report what happened with Yuma Tsukumo, where Kite tells Orbital not to ask anything unnecessary or he will permanently shut Orbital down which upsets him, and thinks to himself that the real enemy of him is Astral, and that he will defeat him at all cost. Orbital asks Kite if he thinks Yuma is his rival, which Kite disagrees and tells him that Yuma is just an idiot.
Meanwhile Yuma is still hanging onto the workers in front of the Heartland building and claiming he won't go away until he gets a heart piece. Tori and the others are still there with the latter saying that a few hours passed and Yuma still doesn't give up. Then suddenly the doors open and Mr. Heartland appears with Dextra and Nistro, with Litterbots trumpeting, where Yuma's friends are surprised to see him face to face. Yuma then calls out to Mr. Heartland by rudely calling him "Old man"(In the dub, Yuma casually says to him "Hey dude!"). Mr. Heartland becomes angry to be called by that name. Tori says it isn't a good start. The workers below try to correct Yuma to call him "Lord Mr. Heartland", but Yuma keeps getting the name wrong.(In the dub, Yuma confuses his gender, calling him "Mrs. Heartland".) Yuma then tells Mr. Heartland about how he couldn't register for the WDC properly and asks him if he can receive a heart piece, though it shows Mr. Heartland still annoyed by Yuma calling him an old man (in the dub, it's changed to Mrs. Heartland). Yuma's friends are amused by how rude Yuma is (in the dub, Caswell says that Yuma need a good selection of words and Bronk says there is a little to choose from). Mr. Heartland tells Yuma that he has heard about it and that it has reached to his warm heart, and that he will grant his wish and gives Yuma a heart piece, then Mr. Heartland notices the pendant Yuma is wearing and asks him about it, where Yuma tells him that it is an important present that his parents gave him. Mr. Heartland says to himself that he has seen the pendant from before (in the dub, Mr. Heartland says that there is something special about Yuma).
Afterwards, with Yuma and Tori alone, Tori congratulates Yuma that he can finally fulfill the promise he made with his father to become the Duel Champion. Astral tells Yuma that he must win since the tournament should have many "Numbers" holders. Yuma tells Astral that he doesn't plan on just winning, where Astral asks Yuma why he doesn't plan on fully winning since that would mean Yuma wouldn't be fulfilling the promise he made with his father. Yuma explains to Astral that he has thought to himself for a long time about what Dueling means to him, and that ever since he met Astral, he started to win despite losing all the time before, but when he lost against Reginald and Kite, he understood that he could lose something important from losing for the first time, but he never hated Dueling despite it.
He tells Astral that Dueling mean bonds and connection to him, and that Dueling and fighting is different. Astral doesn't want to agree to him since he would disappear if he lost. Yuma tells Astral that he understand how he feels and will do anything to save him, but have realized that there is something exceeding from winning and losing. Astral asks Yuma what he will do about Kite, where Yuma answers that he will lose his soul if he lost, but it won't change his Dueling. Then Tori worries what would happen if Yuma really lost his soul, where Yuma tries to comfort Tori, so she tells Yuma to win at all cost in the tournament, which Yuma promises to.
Inside Emperor's Key, Astral questions to himself what is more important than winning. Then it is shown Yuma and his friends all respectively rebuilding their Decks. While in that time Kite stares at his sleeping brother, Hart Tenjo. Next day comes, where the WDC starts with greetings from Flight shows and parades. Mr. Heartland greets all Duelists and explains the rules regarding the World Duel Carnival.
The prelims will go for 3 days in the entire Heartland, and that all Duelists must all accept all challenges from other Duelists. The tournament will have an ante rule of betting their Heart Pieces and that if all Heart Pieces are lost, the participant will be disqualified. In order to enter the finales, the Duelists must gather all Heart Pieces to make a perfect heart.
Mr. Heartland then officially opens the World Duel Carnival. Yuma's friends all run off to find opponents, and suddenly out of no where, Striker appears with his soccer ball stuck full of Duel Monsters cards, and kicks the ball to find his first opponent, which lands on Yuma's face, where Striker challenges Yuma for his first Duel.
The following cards appeared in this episode. Cards in italics debuted here.