is a Japanese manga series written and illustrated by Shinji Wada. It was serialized in Hana to Yume from 1975 to 1982 and collected into 22 volumes. has been adapted into three live-action television series, an original video animation (OVA) series, and three feature films, the last of which was released as Yo-Yo Girl Cop in 2006. It has also inspired four spin-off manga: , a short story collection published in 2004, and , , and , three ongoing series that premiered in Monthly Princess in 2021. Plot A 16-year-old (delinquent schoolgirl) named Saki Asamiya is offered by the police to become an undercover detective to escape prison. She initially refuses, so the police blackmail her by offering to pardon her mother, who is on death row for killing her husband, eventually forcing her to accept. Put under the tutelage of officer Kyouichiro Jin, she is given a metal yo-yo that doubles as a weapon as well as a police badge, and is made to infiltrate high schools around Japan to investigate and stop criminal activities. Her first destination is her former school, Takanoha High School, where Saki's place has been taken by the three Mizuchi sisters and their ring of illegal activities. Characters The bitter heroine of the story, a natural born fighter who enjoys getting into scuffles with various people. Saki is blackmailed into becoming a secret investigator. She never backs down and is very stubborn. Her main weapon is a steel loaded yo-yo capable to function as a weapon. Saki's mentor in the police, a long-haired, English-Japanese man who worked for Scotland Yard. He is cold-blooded and protective of Saki. The man who recruited Saki, a shady police officer who is in charge of the Sukeban Deka program. Saki's mother. She only loved her other daughter Miyuki and abused Saki as a result, and was arrested for beating her husband to death in front of Saki. Despite Saki's efforts to save her from execution, Natsu hates her, especially after Miyuki's death, and later joins Shigaraki in order to have Saki dead. In the TV series, she is a completely different character. She never abused Saki and was not guilty of her husband's death, although she certainly thought so and could not forgive herself for it. Saki's ardent admirer, who calls her "his goddess" and follows her all over the school campus. Saki's best friend. A shy, quiet