Kouji Ibuki shared a childhood friendship with Toshiki Kai and Taishi Miwa in elementary school, introducing them to Cardfight!! Vanguard as a symbol of their bond. Hoping to forge new connections through the game, he deliberately lost matches to let others win, only to face social rejection and isolation. This experience bred deep resentment toward Vanguard. Years later, alien Deletors from Brandt offered him a Link Joker "Deletor" deck to eradicate the game. Each victory with it severed opponents' ties to Planet Cray, weakening the Earth-Cray link. Ibuki accepted, becoming a global menace. His rampage triggered Takuto Tatsunagi's Messiah Scramble tournament to stop him. In the finale, possessed by Deletor leader Oksizz, Ibuki nearly defeated Aichi Sendou and Kai in a two-versus-one fight until Harmonics Messiah empowered Aichi to overcome him, breaking the Deletors' hold. Gifted a purified Link Joker "Messiah" deck featuring "Neon Messiah" by Harmonics Messiah, remorseful Ibuki departed seeking redemption. During his travels, he encountered Rive Shindou protecting the Cray unit Chrono Dran. Learning Rive's former ally Ryuzu Myoujin planned to abuse the time-manipulating Gear Chronicle clan to rewrite history, Ibuki infiltrated the Vanguard association as aide to United Sanctuary branch chief Yuichirou Kanzaki. Tasked by Rive to prepare Rive's son Chrono Shindou against Ryuzu, Ibuki secretly supplied Chrono with Gear Chronicle cards while posing as his rival. He later stole vital "Depend Cards" from Ryuzu, delivering them to Chrono and revealing his role as benefactor. After Chrono awakened Chrono Dran from a card, Ibuki became his open mentor, supporting him until Ryuzu's defeat. Post-Ryuzu, Ibuki reformed the Vanguard association. Investigating U20 tournament participant Kazumi Onimaru, he uncovered Onimaru's possession by Stealth Dragon Shiranui—part of the illegal "Diffride" phenomenon where Cray units control humans. Shiranui served Apostles seeking to revive the entity Gyze. After Chrono convinced Shiranui to defect, the Apostles targeted Ibuki as Harmonics Messiah's avatar to prevent interference. Ibuki shielded Messiah with Chrono's aid and joined the battle to destroy Gyze. In the manga continuity, Ibuki possessed PSY Qualia, enhancing his cardfighting. He gifted the "Blaster Blade" card to Kai in their youth, which later reached Aichi Sendou. As an older student at Fukuhara High, he confronted Aichi about Blaster Blade and defeated Tetsu Shinjou using his Deletor deck. Physically, young Ibuki had short hair covering his right eye. As a teen, he grew taller with longer hair, wearing a white coat with red trim over a dark shirt. His personality shifted from quiet and gentle to cold and reserved after isolation, later adopting a more approachable demeanor in the G era though retaining sternness around Chrono. A skilled martial artist, he could subdue multiple opponents. His cardfighting decks included: - **Deletors**: Focused on "Deleting" opponent's vanguards to nullify power and abilities. - **Messiahs**: Used locking and unlocking mechanics for field control, symbolizing redemption. - **Kagero**: Briefly used against Chrono in an early G-series match.