Heat O'Brien

Season 0
A member of CHAOS decided to do whatever it takes to stop KaibaCorp.

Episode 10

After an incredible bowling strike, Okada walks up to Kasuga Ichiban and introduces himself: Okada has been scouting Ichiban and asks him to join his cause, but Hayashi Hiroshi comments on Okada's choice since he seems "far below The Dragon's level", when Jack calls them CHAOS and lunges at Okada only to be blocked by Heat O'Brien and Bob Utsunomiya. Ichiban is surprised Chaos is actually real and rejects their offer because he hates when party members leave, but Sinbad tells him to be careful since they are as formidable as KaibaCorp, and since he won't join them the easy way, Okada decides it's time to test Ichiban. Okada gives credit to Ichiban for his potential as leader, and their team escapes.

Trivia

 * Adol Christin's post-TS design in Season 6 is based off him.