The protagonist of this story, Aichi Sendou, is a timid young boy in his third year of junior high school. He had been living his life looking backward rather than forward, trying not to stand out. However, he had one thing that kept him going - the Blaster Blade, a card from a card game that was given to him when he was little. That card is the reason why he begins to engage in cardfights, something that changes his life drastically. The name of the card game is Vanguard. The game takes place on a different planet called "Cray", and due to a never-before-seen play system, it becomes popular throughout the world.
Aichi, immediately attracted by Vanguard, meets friends such as Misaki Tokura and Kamui Katsuragi, along with other rivals. Through friendly rivalry with them, Aichi begins to enjoy a fulfilling life. Aichi, however, has a goal: to once again battle with a cardfighter by the name of Toshiki Kai, an aloof and cold-hearted high schooler who has outstanding abilities in the world of Vanguard. He is also the reason why Aichi started playing the game. For him, Kai is the person who introduced him to Vanguard and saved him from his boring life. In order to get better at the game, Aichi puts his heart into it every day. He wishes that someday, he'll be able to battle Kai and have him recognize his worth.
Aichi's ventures in Vanguard eventually lead him to join with Kai, Misaki, and Kamui to form Team Quadrifoglio ("Q4" for short). Together, they enter regional and national tournaments to test their skills against fighters from all over Japan. One particular opponent that Aichi faces is Ren Suzugamori, a powerful but despicable cardfighter who is the leader of Team Asteroid and was once Kai's comrade. Ren eventually makes Aichi awaken a power that he also possesses: Psyqualia, a psychic-like ability that lets its user foresee victory in cardfights. However, Aichi's usage of Psyqualia slowly distorts him into becoming a dark person like Ren. But thanks to Kai's efforts, Aichi decides to no longer use Psyqualia and reverts to his normal self. He and Team Q4 would then go on to defeat Ren and Team Asteroid at the next national tournament and become the national champions of Japan.
Season 2: Asia Circuit
Shortly after Q4 wins the national tournament, a strange phenomenon occurs when Aichi meets a young boy named Takuto Tatsunagi. The Royal Paladin, Shadow Paladin, and Kagero clans of Vanguard have been wiped from existence, and due to this, Aichi's Royal Paladin deck has been changed to Gold Paladin. Aichi reunites with Q4 (excluding Kai) and travels across Asia to participate in the Vanguard Fight Circuit, an invitational multi-stage tournament featuring the world's best cardfighters, for the opportunity to meet and seek answers from the sponsor, Takuto. Throughout the circuit, Aichi, whose Psyqualia has reactivated, encounters a mix of familiar friends and new rivals. One noteworthy rival is Team Dreadnought's Leon Souryu, a man who not has only the power of Psyqualia but is also on a mission to lead the second coming of both his family and the long-lost Aqua Force clan. After losing at the Singapore, Seoul, and Hong Kong Stages of the VF Circuit, Q4 finally manages to win the Japan Stage and gets the chance to meet Takuto, who reveals that a dark entity known as Void is the one responsible for the disappearance of the 3 clans and that it is currently threatening the planet Cray. Furthermore, Leon is exposed as being in alliance with Void as he was the one who allowed the 3 clans to be sealed away. In a final confrontation, Aichi defeats Leon, who had absorbed Void's power. With a reformed Leon's help, Aichi uses his Gold Paladins to drive Void out of Cray and subsequently free the captured clans. Then, the VF Circuit concludes with Q4 crowned as the winning team. Afterwards, life returns to normal, except that Aichi now has a new deck featuring his signature Royal Paladin units as Gold Paladins.
Season 3: Link Joker
Months have passed after the events of the VF Circuit. Aichi enters his first year of high school at Miyaji Academy, which diverges him from most of his friends. At Miyaji Academy, the instructors and students focus on looking towards the future and studying to survive in this age of globalization. One day, Aichi admits he thinks Vanguard can be a future that people can believe in, but in order to prove it, he must use his new deck, a deck in which Royal Paladins and Gold Paladins are combined as one force. Slowly but surely, Aichi must gain friends through cardfighting and help his new team win the newly-formed high school cardfighting championships.