Sousuke Yamada, a third-year Doshisha University rugby team forward (right prop) wearing jersey number 3, boasts a muscular build, dark skin, auburn-brown dreadlocks pulled into a ponytail, and piercing grayish-blue eyes. His physique reflects the demands of his athletic role.

When Natsusa Yuzuki rejoined the team post-hospitalization, Sousuke theorized Natsusa had shed muscle mass rather than height, underscoring his keen focus on physical fitness. Later, he allied with teammates Ethan Taylor and Syouta U to campaign for a "beautiful, sexy female" manager to energize the team—a proposal abandoned after Natsusa flattered the group into accepting Yuu Mashiro’s appointment. This incident exemplifies Sousuke’s recurring tendency to yield to persuasive tactics.

His surname Yamada merges the characters for "mountain" (山) and "field" (田), while Sousuke’s name derives from "religion/sect" (宗) and "herald" (介). Teammate interactions highlight his direct demeanor and loyal camaraderie, cementing his role as an approachable, team-oriented athlete.