The dark haired middle child of the Mizuchi family. She has four hulking bodyguards who follow her around for protection. Ayumi is a drug addict and dealer, and is extremely greedy. However, she is the least evil out of the Mizuchi sisters. Despite her cold demeanor, she is loyal to her father and sisters.   ~!In the OVA she is betrayed and killed by Remi, who gives her a malfunctioning shotgun that backfires, and steals all her money.!~  (Source: Wikipedia)

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! 
 
(Source: ADV Films)

Sukeban Deka centers on Saki Asamiya, a high school delinquent who strikes a deal with the police to investigate her former high school and bust illegal gang activities, in exchange for her mother's pardon. Armed with her metal yo-yo, she fights the Mizuchi sisters, who de facto control the school.
 
(Source: Anime News Network)

Ayumi Mizuchi