T-Bone, known in Japan as Iwamaru (岩丸) is one of the four members of the Light Brigade. He first appeared when called upon Frost (alongside his partner Blaze) after Frost defeated Syrus Truesdale and Tyranno Hassleberry; Frost intended to use them to drag their unconscious bodies to Kaiba Land to lure Jaden (then Duel him), but Sarina, unimpressed with the close-call nature of Frost's victory, sealed him away in a mirror. Intimidated by Sarina, Blaze and T-Bone left the lair to confront their target: Jaden Yuki. After befriending Jaden and his friends (not knowing their names), Sarina sealed Blaze in a mirror and coerced T-Bone to duel Jaden. Despite having the powers of all the other Light Brigade members bestowed into his Deck, he lost.
Following his defeat, he was sealed in a mirror by Sarina, but was freed alongside the other Light Brigade Duelists after Jaden and Aster Phoenix defeated her. In the English version, he is a rapper wannabe, reflected by his accent and choice of words.
The "Iwa" portion of his name in the Japanese version is derived from the word "iwa" (岩), meaning "rock."