Kirihito Tsuji, a first-year Oodachi High student, serves as the sumo club’s coach and reserve member under the epithet "Onikiri Yasutsuna." A chronic lung condition confines his physical stamina to explosive 20-second bursts during matches, compelling him to prioritize tactical ingenuity, technical mastery, and rapid counterattacks. His combat style leverages feints, momentum exploitation, and precision-driven techniques like the Three-Point Throw and Head Twist-Spinal Cut to secure swift victories, blending agility with calculated risk.

Childhood friend of Hinomaru Ushio, Tsuji trained in sumo before diverging due to health limitations. Despite restricted endurance, he maintains rigorous weight training and muscular conditioning rivaling active wrestlers. His analytical prowess and innovative training techniques, such as balance drills on kelp-harvesting boats, elevate the team’s competitive edge. At the Inter High Tournament, he substitutes for the injured Kei Mitsuhashi, marking his debut and igniting a renewed fervor for sumo.

Post-timeskip, Tsuji enters professional sumo with Nagato Stable under the shikona "Onikiri," rising to maegashira through adaptability and tenacity. Physically, he possesses a slim yet defined musculature, long black hair, and glasses, with heightened sensitivity to cold and strong odors—traits possibly tied to his respiratory condition. Academically weak in Japanese history, he excels in strategic analysis and problem-solving. Personal hobbies revolve around solitary pursuits: cinema visits and web browsing.

Initially a strategist, Mitsuhashi’s influence propels Tsuji into active competition, reconciling his yearning to compete with physical constraints. His emotional arc culminates in a steadfast dedication to sumo despite medical barriers, embodying resilience and inventive adaptability. This journey frames him as an emblematic figure of transcending adversity via strategic ingenuity and unyielding resolve.