Sonoko carves her legend as the fabled Wednesday Cinderella, navigating Hakone pass each Wednesday behind the wheel of a white Porsche. Her mysterious weekly appearance draws crowds of motorcycle riders eager to witness her passage.

Renowned for formidable driving skill, she becomes a primary target for the protagonist Kenji's ambition after he learns of her. Racing against her involves significant danger, underscoring her challenging nature and advanced capabilities.

Within the narrative, Sonoko emerges as a more developed figure compared to other supporting characters. Her encounters with Kenji form a significant dynamic, defined by the clash in their driving styles and motivations. This friction fuels the core tension during their thrilling contests.

Sonoko's background origins, personal history, and relationships outside her identity as Wednesday Cinderella remain undisclosed. Her portrayal and story arc are confined to the original film's context, centered on the races and their inherent risks, with no extension into additional seasons, movies, OVAs, or spin-offs.