Arthur is an American soldier who deserted and joined the Kentauros motorcycle gang in Yokohama. His military desertion marks him as an outsider within the group, fueling a volatile disposition. He develops a fierce rivalry with Ken, a new gang member, over their shared romantic interest in a woman called Lady. This rivalry fuels the central narrative conflict. Arthur's motivations are more complex than Ken's, his actions shaped by both his pursuit of Lady and the lingering trauma from his military past. Though initially an antagonist, his nuanced portrayal reveals complexity, making him a more sympathetic figure. Their conflict culminates in Arthur challenging Ken to a decisive motorcycle race to resolve their rivalry. The character is inspired by a real member of the Kentauros gang, lending authenticity. His role underscores themes of competition and personal strife within the motorcycle racing subculture.