Rion Sawai attends Eigadai Affiliated High School as a dedicated sumo club member. His imposing frame stands at 183 cm tall and weighs 149 kg, with a large, round physique complemented by brown hair, brown eyes, and a distinctive light brown beard concentrated on his chin. During matches, he dons the Eigadai Sumo Club’s red mawashi belt.

Though his pre-bout trash-talking suggests a foul-mouthed demeanor, Rion is fundamentally kind, responsible, and academically accomplished, maintaining excellent grades. He approaches sumo with intense focus, prioritizing calm observation of opponents’ movements. His physical dominance allows him to overwhelm less robust rivals, yet his verbal tactics draw criticism from teammates like Daniel Stefanov, who find them at odds with Rion’s otherwise considerate character.

At the National High School Sumo Championship’s group bout finals—following Kei Mitsuhashi’s injury withdrawal—Rion faced Kirihito Tsuji. Their first match saw Kirihito aggressively drive Rion toward the ring edge, but Rion redirected his momentum, extending the bout past Kirihito’s typical 20-second stamina limit. Simultaneous falls forced a contested ruling and rematch. In the rematch, Rion attempted to prolong the fight upon noticing Kirihito’s labored breathing, only for Kirihito to deploy the "Head Twist: Spiral Cut" technique for victory.

Rion dislikes the nickname "Leon," given to him by Daniel Stefanov.