TV-Series
Description
Kouji Ibuki was a quiet, gentle elementary school classmate of Toshiki Kai and Taishi Miwa. He introduced both to Cardfight!! Vanguard, sharing Blaster Blade with Kai and sparking their interest. His attempts to make friends by intentionally losing matches backfired, leading to resentment and refusal from others to play, reinforcing his loner status.

Years later, manipulated by the Deletors from planet Brandt, Ibuki embraced their goal to sever Earth's connection to Cray. Using a Link Joker "Deletor" deck, he deleted opponents' units upon victory, weakening Cray's ties and causing physical cards to disintegrate. As the primary antagonist in the Neon Messiah tournament, he faced Aichi Sendou and Kai while possessed by the Deletor leader Oksizz. Defeated by Aichi wielding Harmonics Messiah, Ibuki was freed from control. He received the purified Neon Messiah Link Joker deck as a symbol of redemption and departed to wander the world seeking atonement.

During his travels, Ibuki encountered Rive Shindou, who revealed Ryuzu Myoujin's plan to abuse Gear Chronicle's time-manipulation. Entrusted with Gear Chronicle cards and Depend Cards, Ibuki infiltrated the Vanguard Association as Yuichirou Kanzaki's subordinate and coach of Team Demise. He anonymously sent Gear Chronicle cards and a map to Rive's son, Chrono Shindou, guiding him to Card Capital 2 to begin his journey. Ibuki periodically tested Chrono's growth through cardfights, employing tactics like psychological taunts about isolation. After betraying the Association and stealing Depend Cards for Chrono, he revealed Ryuzu as their shared enemy and his role in supplying Chrono's deck.

Ibuki later transitioned to a mentor role for Chrono, adopting a calmer though occasionally reserved demeanor. He organized allies from prior generations against Ryuzu, participated in G-quests, and lost a rematch to Chrono. He confronted Kazumi Onimaru, possessed by Stealth Dragon Shiranui, debating ideologies of destiny. When the Apostles of Gyze targeted him as Neon Messiah's avatar, he defended Messiah with Chrono's aid. Post-Ryuzu's defeat, he reformed the Vanguard Association, sponsored the U20 championship, and investigated Diffride phenomena involving Cray units possessing humans.

Physically, Ibuki grew from a shorter child with eye-covering bangs to a taller adolescent with grey hair, red eyes, and a distinctive white-and-red coat. He demonstrated martial prowess, incapacitating United Sanctuary employees and defeating Shouma Shinonome in physical confrontations. In non-anime media, he temporarily wielded PSY Qualia. His central fighting philosophy remained: "a fight reveals everything about a person."