This is a movie made after the completion of Sukeban Deka II TV series starring Yoko Minamino as Saki Asamiya. It also introduces the new Sukeban Deka Yui Asaka as the third Saki Asamiya.
Saki Asamiya (a.k.a. Yoko Godai, Saki Asamiya II, Shiori Saotome) has returned to being a normal high school student. Now retired from her assignment as the second Sukeban Deka, she's concentrating on her study to pass her college entrance exam. One day she gets embroiled in a kidnap attempt of a teenager named Kikuo (Tetta Sugimoto) in a bus. He turns out to be an escapee from an island that trains delinquent high school student to be terrorists. There's a plan to take over Japan by these student terrorists. Kikuo has a young sister Megumi (Ayako Kobayashi) who works in a pub. Saki finds her from the clue Kikuo left. Megumi begs Saki to save Kikuo. Saki with Okyo, and Yukino goes to rescue Kikuo, and other students who are being held in the secret island.
This is the final chapter of Sukeban Deka II series, and the last appearance of Yoko Minamino as Saki Asamiya. She's joined by the new Sukeban Deka, Yui Kazama to battle the group of terrorists running a school in a secret island. She is given a special heavy duty Yo-Yo by Nishiwaki (Keizo Kanie) to battle the force run by Hattori (Masato Ibu).
Sukeban Deka II series is the favorite of most fans who followed this series. Yoko Minamino really carried this series, and made it a success. Her charm is evident in this movie as well. Supported by more than usual cast of Yui Asaka, Ayako Kobayashi, Tetta Sugimoto, and of course Haruko Sagara and Akie Yoshizawa, this movie really is a fitting finale to an excellent series.
This being the best of the Sukeban Deka movies in my opinion, is worth a watch if you can find a copy.