Mad Dog

Mad Dog, known in Japan as Inukai「犬飼」is Zane's opponent in the Underground Duel.

In the Japanese version, "Mad Dog" is actually his nickname, and translated literally, his given name means "Dog Owner". In the English dub, his voice is an imitation/parody of Mike Tyson. In the dub, his voice is very high-pitched and childish, contrasting with his physical appearance.

Deck
Mad Dog plays a Slime Deck which focuses on various disrupting strategies meant to impede his opponents' ability to activate cards in addition to cards that gradually inflict Direct Damage under such circumstances such as "Rust Machine Virus of Acid".