"Cardfight!! Vanguard G" is the sequel to the original "Cardfight!! Vanguard" series, set in a world where the card game Vanguard is a central part of culture and competition. The story centers on Chrono Shindou, a carefree and impulsive middle school student who initially has no interest in Vanguard. His life changes when he encounters a mysterious card, "Blaster Blade," which leads him to meet Tokoha Anjou and Shion Kiba, fellow students who are passionate about the game. Together, they form a team and begin their journey into the competitive world of Vanguard.

Chrono's involvement in Vanguard deepens as he discovers his connection to the "Gear Chronicle," a clan of cards tied to time manipulation. This revelation propels him into a larger conflict involving the "Stride Gate," a mysterious phenomenon threatening the balance of the Vanguard world. As Chrono and his friends compete in tournaments and face off against skilled opponents, they uncover the truth behind the Stride Gate and its connection to a shadowy organization known as "Ryuzu Myoujin." This group seeks to exploit the power of the Stride Gate for their own purposes, endangering the future of the Vanguard universe.

Throughout the series, Chrono and his team encounter a diverse cast of characters, each with their own motivations and ties to the Vanguard world. Notable figures include Kamui Katsuragi, a cheerful and determined fighter; Taiyou Asukawa, a prodigy with a tragic past; and Am Chouno, a mysterious girl with a connection to the Gear Chronicle. The narrative explores themes of friendship, rivalry, and self-discovery as the characters grow both as players and individuals.

The plot is structured around various tournaments and battles, showcasing strategic card gameplay and the evolving dynamics between characters. As the story progresses, the stakes escalate, culminating in a climactic confrontation with Ryuzu Myoujin and the resolution of the Stride Gate crisis. The series balances its action-packed card battles with character-driven storytelling, providing a cohesive narrative that builds on the lore of the Vanguard universe.