Brier, known in the Japanese anime as Kohara, is a Ra Yellow Duelist and the brains behind the "Duel Giant" incident.
Fitting his rank in Ra Yellow, Brier is a very skilled and intelligent Duelist, but is shy in crowds (suffering from stage-fright and an inferiority complex) and tends to become extremely nervous around people. He also harbors a deep grudge against Obelisk Blue students for their constant arrogance and bullying. When dueling anonymously, Brier's personality changes drastically becoming much more aggressive and confident. Brier also cares deeply for Beauregard, offering to surrender himself to Jaden after their duel if he let his friend go.
Vindictive after being bullied for so long by Obelisk Blue students, Brier teams up with Beauregard to combat both his detractors and his stage fright. The two team up to create a combined persona called the "Duel Giant." Beauregard played the part of the Duelist while Brier fed him instructions and dialogue via a radio headset during Duels. The duo took revenge on several Obelisk Blue students using Beauregard's imposing size to terrorize the bullies into unauthorized Ante Duels, after which they stole the Obelisks' rare cards.
Eventually, word reached Dr. Crowler who then "hires" Jaden to defeat the "Duel Giant"– intending to expel him from the academy if he fails. After watching Brier lose to an Obelisk Blue bully, Jaden and Winged Kuriboh notice a suppressed fighting spirit in Brier, which they identify as that of the "Duel Giant." However, Brier and Beauregard flee before Jaden can challenge them. At midnight, Jaden and his friends wait for the Duel Giant, finding him after he defeats the bully from the previous afternoon. Jaden challenges the Giant to a match. He quickly exposes Brier and Beauregard's trick, and convinces the two to battle out in the open in exchange for not turning them in. Brier and Beauregard return the stolen cards and resolve to become stronger as individuals together.
Brier made a cameo in episode 179, watching Jaden's Graduation ceremony.
When Beauregard and Brier Duel alongside each other as the "Duel Giant", they use a Goblin Deck, which includes high-ATK strength creatures such as "Giant Orc" that can have its drawback removed by the Union Monster "Second Goblin". The visual relationship between these cards mirrors their own—a large, powerful being supported by a much smaller one.