The time was spring 1343 at the end of Won Dynasty in China. The Mongolians, the Hans and Koryo migrants were in conflict with one another. In the village of Sanme-hyon, Jinha, the son of wandering Koryo people and Soli, a daughter between a Mongolian general and his concubine, share a brief romance. When Soli is taken away, Jinha tells her he will wait for her. When Jinha meets Soli again, he finds that she is to be married off to Junkwang, the son of a wealthy family. Soli's stepbrother helps the couple to run off, so they may continue their love. But the enraged Junkwang and his men head off on a quest to get his bride-to-be back in his arms.

Ami (Minase Yashiro, in her film debut) is a tough but otherwise average high school girl, trying to lead a normal life. Her world comes crashing down when her brother and his friend are killed by ruthless bullies. As Ami tracks down the ringleader, she is surprised to discover the bullies' association with a sinister ninja yakuza family. When she goes after her revenge, she soon finds herself in over her head and minus her left arm. Barely surviving, Ami escapes and seeks out shelter from two kindly garage mechanics. They take pity on her, fitting her with a high-powered machine gun where her arm used to be. She then teams up with the chainsaw-wielding mother (Asami) of her brother's slain friend and together they unleash an unholy, non-stop, over-the-top kill fest against the equally creative machinery (drill bra, flying guillotine) of their relentless ninja enemies. When the very idea of THE MACHINE GIRL was introduced to the world, an internet phenomenon was launched. Many believed a film so outrageous couldn't possibly exist. But here it is, in all its uncut, gory glory from the creators of DEATH TRANCE, MEATBALL MACHINE and SUKEBAN BOY.