Sabii serves as the twin brother of Wabii, mirroring his sibling in every physical aspect—both possess a large, obese build and wear identical pink vests, blue shorts, golden wristbands, and blue-and-green helmets adorned with yellow eye markings. The sole distinctions lie in the number of helmet ponytails and forehead dots. Reflecting their synchronized bond, Sabii and Wabii consistently speak in unison.

As battlers of darkness within the Spirits World, Sabii and Wabii first intercepted protagonists Shunta Mogami and Yoku Albatrosa during their journey. Unable to select individual opponents, the twins initiated simultaneous duels: Sabii battled Yoku while Wabii faced Shunta. Sabii lost this encounter and retreated with his brother. Later, both joined fellow battlers of darkness in assaulting General Inui for The BoarTwelveGodKing Calamity-Boar, suffering another defeat.

At a subsequent gathering of battlers, Sabii and Wabii declared readiness to duel each other for General Inui's newly obtained The RoosterTwelveGodKing Gale-Phoenix. Sabii vowed no leniency toward his twin. However, after witnessing contender Kabuto's overwhelming power, both brothers withdrew. Yoroi ultimately challenged Kabuto and claimed Gale-Phoenix.

Sabii wields a Zodiac X-Rare deck indistinguishable from Wabii's, exhibiting such synchronicity that both draw identical cards in combat. His verified cards include The MagicalTwinsDeity Geminize, The ScorpioKnight Scor-Spear, and The ShineCentaurusDeity Sagitto-Apollodragon. His only recorded battle result remains a loss to Yoku in Episode 4.