Leonardo Sturges, called Leo, is a foreigner working initially as a ninja actor at Edo Wonderland. He crosses paths with Jotaro Aragaki and his daughter Rei during their theme park visit, follows them home, and requests shelter. His arrival coincides with a critical juncture in Jotaro's career, impacting the gymnast's choice to continue competing rather than retire.

A former ballet dancer, Leo's background in this discipline informs his physical grace and movement understanding. Individuals in black suits pursue him due to unresolved matters connected to his ballet career. Seeking refuge with the Aragaki family, he integrates into their household dynamic.

Within the family, Leo forms a bond with Rei, offering her emotional support as she navigates feelings about her father's career and her own unexpressed needs. He assists Jotaro by providing unconventional perspectives on athletic performance, drawing parallels between gymnastics and ballet. His presence contributes to Jotaro's efforts to adapt techniques and overcome physical limitations.

An incident during a gymnastics routine results in Leo's ninja costume accidentally coming off, revealing he wears a sports bra or compression vest underneath.

As the series progresses, Leo's storyline involves evading the pursuing agents. This culminates in an attempt to leave Japan, triggering an airport chase sequence involving the Aragaki family. This event reinforces his connection to the family before his situation resolves.

Leo evolves from a comedic outsider seeking asylum to an earnest participant in the family's challenges. His journey involves processing his past while supporting Jotaro's athletic comeback and Rei's emotional well-being, ultimately becoming part of their household.