"Sukeban Deka" centers on Saki Asamiya, a teenage girl who is released from juvenile detention to serve as an undercover agent for a secret government organization. Tasked with infiltrating high schools to uncover and dismantle criminal activities, Saki operates under the guise of a delinquent transfer student. Her primary weapon is a yo-yo, which she wields with exceptional skill, using it to disarm and incapacitate adversaries. The series blends action, mystery, and drama as Saki navigates the complexities of her dual identity, balancing her mission with the challenges of teenage life.

The narrative unfolds episodically, with each arc focusing on a different school or criminal organization. Saki’s investigations often reveal corruption, exploitation, and violence within the student body or faculty, requiring her to confront powerful adversaries while maintaining her cover. Her interactions with classmates and teachers add depth to the story, as she forms alliances and uncovers hidden truths about the institutions she infiltrates. The series also explores themes of justice, loyalty, and the moral ambiguities of undercover work, as Saki grapples with the ethical dilemmas of her role.

Supporting characters include Saki’s handler, a government official who provides her with missions and guidance, and various classmates who become entangled in her investigations. Antagonists range from ruthless student gang leaders to corrupt educators, each presenting unique challenges that test Saki’s resolve and combat skills. The series maintains a balance between intense action sequences and character-driven moments, offering a mix of suspense and emotional depth.

"Sukeban Deka" is notable for its portrayal of a strong, independent female protagonist in a genre often dominated by male leads. Saki’s resourcefulness, determination, and moral compass drive the narrative, making her a compelling central figure. The series’ blend of high-stakes action and social commentary on issues within educational institutions contributes to its enduring appeal.