Simeon Nagid masters Tento Seiin Ken, a Nahash tribe martial art centered on absorbing an opponent's chi to augment his own physical prowess and unleash devastating attacks. Driven by the ambition to obtain the List of Hope and the Jewels containing the souls of Shuken and Yahma—key figures in Hokuto Shinken's history—he captures Erika Arendt, overpowering Yasaka's defense. This act serves his broader scheme to modify or re-create the world using these ancient artifacts' power.

He possesses formidable combat abilities, including superhuman physical attributes and potent chi manipulation. His signature technique, Tento Hakuja Shu (Heaven Dipper White Snake Strike), unleashes chi-constructed arms against foes. Simeon operates at "at least Large Country level" in power tier, evidenced by damaging Kenshiro Kasumi and slaying Charles de Guise—a departure from the manga where Liu Feiyan killed Charles. His Faster-Than-Light reaction speed further intensifies through chi absorption.

Simeon acts alongside fellow Tento practitioners like Van der Kool, who shares similar martial arts and objectives. However, Simeon's core focus remains exploiting the List of Hope and the Jewels to achieve his world-altering goals. Explicit details regarding his origin or development across other media remain unspecified, though his actions consistently establish him as an antagonist fixated on seizing and misusing these mystical items.