Aichi Sendō evolves from a timid, bullied youth into a layered protagonist shaped by his bond with the card game Vanguard. His gentle, introverted nature stems from enduring childhood bullying, but receiving the Blaster Blade card from Toshiki Kai sparks his journey toward self-assurance. Through cardfighting, he cultivates resilience, forming friendships and leading Miyaji Academy’s Cardfight Club. His growth remains intertwined with PSYqualia—a psychic link to the planet Cray—which amplifies his strategic prowess yet threatens his morality. This duality manifests in corrupted phases: under the Shadow Paladins’ influence or a PSYqualia Zombie infection, his demeanor hardens into cold politeness and battle-focused sadism. Alternate timelines explore darker paths, such as an antagonist role in Jammer, where distorted memories and unchecked PSYqualia drive him to eradicate Vanguard. His deck’s evolution—from Royal Paladins to Shadow Paladins and Gold Paladins—mirrors internal struggles, emphasizing themes of unity and sacrifice. Key cards like Majesty Lord Blaster and Liberators reflect adaptive strategies, prioritizing aggressive field-building and multi-attack tactics. Physical changes parallel his psychological shifts: initial middle-school red sweaters give way to high-school blazers, his signature blue hair and right bang altering subtly during corruption, signaling fractured mental states. Critical arcs test his resolve, including self-sacrifice to contain Link Joker’s chaos, leading to isolation guarded by the Quatre Knights. Redemption emerges through allies’ efforts, though alternate timelines like the -IF- storyline reveal unresolved trauma fueling his desire to destroy Vanguard, resolved only through timeline-restoring confrontations. Beyond PSYqualia, his abilities span memory manipulation and spiritual bonds with Cray, enabling direct communication with card avatars and cross-dimensional influence. Expanding across media, his legacy endures in films like *Neon Messiah*, where he partners with Kai against existential threats, and spin-offs exploring divergent fates. In *Cardfight!! Vanguard G*, he supports allies abroad, cementing his status as a revered figure within the Vanguard community.