Daniel Stefanov, a Bulgarian exchange student at Eigadai Affiliated High School, participates in its sumo club. Light-skinned with neck-length blonde hair and blue eyes, he possesses a large muscular build, standing 199 cm tall and weighing 131 kg—the series' second-tallest wrestler. Outside sumo, he typically wears a large red jumpsuit; inside the ring, his attire features a red mawashi.

His fascination with Japanese culture, sparked by watching legendary yokozuna Yamatokuni's bouts, drove him to Japan. He learned Japanese through picture books and exclusively uses honorific speech (keigo) with all individuals, irrespective of age or status. Despite not speaking English, he frequently assigns English nicknames to teammates. Laid-back and naturally popular among girls due to the rarity of Caucasian sumo wrestlers in Japan, his hobbies include football and visiting Japanese temples.

In sumo, Daniel carries the unofficial moniker "Holy Sword - Excalibur," as foreigners are ineligible for formal "National Treasure" epithets. His competitive record shows no individual tournament wins, contrasting with teammate Jin Yomoda. Despite his physical advantages, he struggles to maximize height and weight during matches. His technique focuses on a left-arm clamp—perfected by Yamatokuni and Kuze Sōsuke—and a variant called the "Great Serpent Cleaver," using his reach to hook opponents' mawashi belts. Shinya Ozeki countered this move with a beltless arm throw. Daniel persists despite losses, prioritizing long-term improvement to eventually defeat elite wrestlers.