Ryo Kawasaki, a first-year student at Shin Koshigaya High School, anchors the baseball team as starting shortstop. She joined the club during its revival phase alongside classmate Sumire Fujita, both leveraging prior experience from external leagues. Her shortstop position pairs strategically with Sumire at second base, solidifying their role as the team's core middle infielders. Their on-field chemistry features frequent playful teasing during defensive plays, defining their dynamic in games.

Ryo contributed from the club's early rebuilding stages after its hiatus, participating in practice matches and official tournaments like the Saitama Prefecture Tournament. Volume 8 of the manga showcases her as the cover character during a narrative arc centered on a revenge match against Yanagi Okawagoe High School. This storyline depicts Shin Koshigaya trailing by three runs in the fourth inning, with strategic adjustments and Ryo's performance fueling their comeback effort.

Physically, she possesses grey hair, lilac eyes, and a height of 1.52 meters.