The movie opens with Yui Kazama and her sisters investigating a series of break-ins at a high-tech research facility. As they close in on the suspects, they discover that they are actually students who were blackmailed into stealing the research by the Juvie Security Bureau. Yui is appalled by their methods and confronts Sekin about it, but he brushes her off and orders her to continue her missions.
Feeling betrayed by the organization she once believed in, Yui quits the bureau and goes off on her own, taking odd jobs to make ends meet. Meanwhile, Sekin continues to push his agenda and even orders the assassination of a prominent government official. Yui and her sisters, along with a group of young outcasts led by a girl named Saeko, decide to take matters into their own hands and stop Sekin once and for all.
Their journey takes them across Japan and into the heart of Sekin's stronghold, where they engage in a final showdown with his triple-bladed yo-yo wielding agents. In the end, Yui and her sisters emerge victorious, but not without a heavy toll. Saeko sacrifices herself to save Yui and her sisters, leaving them with a renewed sense of purpose and the knowledge that they will always fight for what is right, no matter the cost.