Sukeban Deka.

The last time Saki left school it was to change her school uniform for prison greys, but when the Feds needed someone to infiltrate a ruthless criminal organization operating within an exclusive high school, they knew they needed the baddest bad girl of them all! Now Saki's back on the streets for the ultimate final exam, armed with a top-secret weapon that only LOOKS like a yo-yo, and a license to use whatever force necessary to achieve her goal. Saki's lovely, lethal and ready to lay it all on the line-because if she fails this test, the next outfit she'll be wearing is a body bag!