Syoko Kobayashimaru is a Hakuoh Academy student and dedicated Space Yacht Club member with grey eyes and black bobcut hair covering the left side of her face. She wears the academy uniform with a green Yacht Club hoodie during standard activities, adopting a blue police officer costume for specific missions like the Princess Apricot raid. Peers such as Lynn note her slightly deadpan demeanor and maturity beyond her years.

During the Odette II's practice cruise, she conducts pre-flight checks, monitors refrigeration systems, and operates bridge consoles. She plays a critical electronic warfare role against the Lightning 11, managing radar systems to detect enemy ships and jam transmissions. In the Golden Ghost Ship Arc, she assists in planning practice cruises and participates in Gruier Serenity's club integration.

Later, during the Hakuoh Pirates Arc, she supervises first-year simulator training and joins the Bentenmaru's temporary crew during their quarantine. Aboard the Bentenmaru, she operates radar during an unplanned FTL jump and participates in the Princess Apricot raid in her police costume, later aiding Jenny Dolittle's rescue by evading the Hugh and Dolittle fleet.

In *Abyss of Hyperspace*, she collaborates on a misinformation campaign against the Yggdrasil Group, discovering a surveillance bug on Odette-kun at a cleaning facility. After graduating, she remains connected to the Yacht Club, assisting with recruitment during spring break.