Kiriko Yoshitoku attends Asakusa Girls High School and serves as the dedicated mechanic within Rin Namiki's Jet Racing club. Her responsibilities encompass all maintenance for the team's jet ski, the Orcano, requiring technical expertise to source optimal replacement parts and ensure its competitive readiness.

Even before the club's official formation, Kiriko secretly maintained the Orcano, preserving its function despite the school lacking a team. This covert activity caught Misa Aoi's attention to the jet ski's condition, leading to Kiriko's recruitment after both Misa and Rin witnessed her working on the vehicle. Her primary motivation for joining was the freedom to continue working on the Orcano without restriction.

Kiriko possesses brown hair, blue eyes, and freckles. Her typical tomboyish appearance features pigtails and mechanic gloves. Personality assessments indicate selflessness and dedication to helping others without expectation of reward, exemplified by her statement: "I don't need a reason to help someone in need," alongside a strong sense of duty. Unofficial fan interpretations debate her personality type, proposing ISTJ (emphasizing analytical skills, rule adherence, diligence) or Enneagram Type 8 (highlighting assertiveness, independence, and a protective nature beneath a confrontational exterior).

Her background reveals initial difficulty forming friendships and a sense of isolation prior to joining the team. Her bond with Rin Namiki and involvement in jet racing fostered personal growth centered on teamwork and friendship. While naturally skilled with machinery, she did not initially participate as a racer.