This is the original Sukeban Deka series staring Yuki Saito as Saki Asamiya.
Kurayami Shirei (Hiroyuki Nagato) who works for Naikaku Johoshitsu (Inner cabinet Intelligence Division) recruits Saki Asamiya who's a boss of girl's gang (Sukeban in Japanese). He needs someone who can work covertly in high school to prevent criminal activity conducted in high schools. Saki's mother is in prison, Kurayami Shirei makes a deal with Saki to suspend her mother's execution if she worked for him. Saki accepts the offer and starts her detective (Deka in Japanese) work.
Based on a comic by Shinji Wada of the same title, this is the original translation of Sukeban Deka series, and is the most edgiest of the trilogy which spanned from 1985 to 1987. The series becomes increasingly campy as it progresses. There's a perpetual cloud over Saki's head as a child of a convict, and she works for the sake of reducing her mother's prison terms.
This series is comprised of 24 episodes, and a 25th "Making of Sukeban Deka" special. Saki gradually finds out who the king pin behind all the crime is and her true relation to him as the series progresses.
This series catapulted Yuki Saito's career, and in tern she succeeded in making this series a success. High school student solving crimes in high school was a novel idea and attracted many fans of the series.
The Sukeban Deka is still being produced from time to time in movies attesting to its popularity. This was the seminal attempt, and was a success that primed the success of all subsequent series.