Ryoko Mochizuki is a first-year student at Asaka Academy and an active member of its rifle shooting club. She possesses long brown hair extending to her back and blue eyes. Her standard outfit is the Asaka Academy uniform: a white short-sleeved collared shirt with buttons, neatly tucked into a gray pleated skirt, worn with long white socks and laceless brown shoes.

Her demeanor is typically reserved, yet she exhibits confidence in specific scenarios like announcing competition lineups for shooting events. She keenly observes others' performances, offering praise when recognizing skill. During practices and competitions, she emphasizes consideration for concentration, actively avoiding disruptive behavior.

Within the club, she trains alongside fellow first-year Karen Sakashita. She participates in team activities and practice competitions against rival schools such as Chidori High School, collaborating with club president Akira Shinonome, vice president Misa Kuroi, and Karen. Her routine focuses on refining rifle shooting techniques and preparing for tournaments.

She is aware of the club's history, including knowledge of a prior unsuccessful iteration. This awareness does not diminish her engagement; she remains dedicated to the current club's pursuits.