Cardfight!! Vanguard

Kids from all over town converge to play Vanguard, a card game that seems to be the biggest thing going around. A timid boy, Aichi Sendō, has a rare card, the Blaster Blade, which makes him a target for Katsumi Morikawa, a player who wants to use Aichi's card to get revenge on another player, Toshiki Kai. After school, Morikawa and his buddy Yūta Izaki steal Aichi's Blaster Blade from him. Aichi runs to a card shop called Card Capital to find that Morikawa lost it in a bet against Kai. It is then that Aichi and Kai meet and play a round of Vanguard with Blaster Blade as the prize. Before the match, Kai gives Aichi Blaster Blade in the hopes of him using it effectively against him. During the course of the match, Kai teaches Aichi the rules of playing Vanguard. As the fight goes on, Aichi reveals that he has met Kai before when summoning his ace, Blaster Blade, which Kai gave to him long ago, stating that it was because of him that he wants to learn more about Vanguard.

After Aichi plays Blaster Blade, he and Kai recall their first meeting. Back then, after seeing a young Aichi beaten up, the young Kai cheered him up by giving him Blaster Blade, and he told Aichi to imagine himself as a strong warrior like the card. With that in mind, Aichi got absorbed into Vanguard, creating his own deck in the hopes of playing against Kai, who had already moved away by then. Back to the game, Aichi deals a bit of damage to Kai, who retaliates with his ace card, Dragonic Overlord. It wipes out Aichi's units and greatly damages him. All seems lost until Aichi draws a "Heal Trigger", which allows Aichi to stay in the game for one last turn. Aichi launches a final attack with Blaster Blade, which breaks through Kai's defenses and deals one more point of damage to Kai, thus giving Aichi the win. A day later, Aichi revisits the card shop. Despite thinking that Kai would not show up after being defeated, Aichi is glad to see that Kai returns.

Aichi's little sister, Emi, is worried by Aichi's different behavior as of late. After school, Emi sees Aichi with Morikawa and Izaki, who want him to go with them to the Card Capital. However, Emi misinterprets the situation as Aichi hanging with the wrong crowd. Concerned for her brother, she secretly follows the trio to the Card Capital. There, Emi is astounded by all the people in the shop, icluding Aichi, Morikawa, and Izaki, playing Vanguard. It is then that the card shop's manager, Shin Nitta, appears and introduces Emi to the world of trading card games. Emi and Shin then observe a cardfight between Aichi and Morikawa. The battle ends with Aichi winning without taking any damage. Watching Aichi play, Emi sees how much her big brother has changed because of Vanguard. And so, she has become supportive of Aichi playing the game.

After taking a look at Aichi's deck, Shin decides to show him "something nice". So, Shin has Aichi battle Misaki, who, despite working at the card shop, has never actually participated in a Vanguard fight before. Nonetheless, after Shin gives Misaki a special deck, she and Aichi begin their cardfight. In the midst of the battle, Misaki shows that she knows more about the game than she lets on as she draws multiple cards and calls her ace card, the Grade 3 CEO Amaterasu. Using the "Twin Drive" ability that Grade 3 cards have, Misaki defeats Aichi. Through this loss, Aichi learns that he has much more to know about Vanguard if he ever wants to play against Kai again.

Aichi goes to the card shop to buy a booster pack in the hopes of getting a Grade 3 card. When he arrives, he sees a grade-school kid, Kamui Katsuragi, convincingly defeating Izaki in a cardfight. Aichi challenges Kamui, but he refuses, noticing that Aichi is not a strong player. Then, after Kamui beats Morikawa in a cardfight, Aichi tries to buy a booster pack. Suddenly, Emi appears, and Kamui immediately falls in love with her. Before Aichi could buy a pack, Emi drags him back home while Kamui looks on, thinking that the two are boyfriend and girlfriend. Later, Aichi buys a booster pack and is pleased to find that the pack contained a Grade 3 card, Solitary Knight, Gancelot. Just then, Kamui shows up and challenges Aichi, demanding to get Emi if he beats him. Although Aichi misunderstands Kamui's intentions, he and Kamui begin their Vanguard fight. Kamui uses powerful cards like Genocide Jack and King of Swords to quickly deal a ton of damage to Aichi, who strikes back by using his newly-acquired Solitary Knight, Gancelot. But in the end, Aichi loses to Kamui after he calls his ace card Asura Kaiser. Afterwards, Emi arrives and tries to get Aichi home, and it is then that Kamui learns that the two are actually siblings. Now, hoping to get closer to Emi, Kamui starts referring to Aichi as his "big brother", although Aichi is not exactly glad about it.

Aichi and his friends decide to go to a different card shop called PSY. There, they try out the shop's special Vanguard Fight Stage. It oddly reacts to Aichi, which leads to a woman, Kourin, challenging him to a cardfight. When the two begin the battle, Aichi is surprised that the stage brings the cards to life. Aichi and Kourin, who both use a Royal Paladin deck, continue their battle, until Aichi makes a bad decision in not guarding one of her Vanguard's attacks, ultimately leading to his defeat. Afterwards, another woman, Suiko, gives Aichi the card The King of Knights, Alfred as a special memento for visiting the card shop. Later, Aichi learns from Morikawa that the card shop they visited has disappeared.