Ryō Shinonome, a skilled baseball rival to Tsubasa Arihara since their junior years, initially dismisses the inexperienced girls' baseball team at Rigahama Municipal High School. She believes Tsubasa is not taking baseball seriously by playing with less skilled teammates instead of pursuing higher-level competition. Ryō's singular ambition is to become a professional baseball player. She plays third base, bats right-handed, throws right-handed, and wears jersey number 5.

Physically, Ryō possesses long black hair reaching her buttocks. Her bangs sweep to the left, and hip-length strands frame either side of her face. She has distinctive red eyes. Her surname "Shinonome" translates to "dawn" or "daybreak," and her given name "Ryō" means "dragon."

Her perspective shifts during a pivotal tryout for a competitive team. Despite a strong individual performance, she fails. Unexpectedly, the Rigahama girls' baseball team supports her with enthusiastic cheering, mirroring Tsubasa’s past motivational actions. This collective encouragement causes Ryō to recognize the value of teamwork and camaraderie, elements she previously undervalued. Though she does not initially disclose the reason for her failure, the experience softens her rigid outlook. She subsequently joins the Rigahama team, transitioning from a detached rival to an integrated member committed to the group’s growth. While maintaining her professional aspirations, she begins contributing to team training and strategy, acknowledging that shared support enhances both individual and collective goals.

This development concludes her initial role as an antagonist, establishing her as a key player whose expertise elevates the team’s overall skill level.