The plot follows an orphaned Japanese schoolgirl whose life is destroyed when her brother is killed by a son of a Ninja-Yakuza clan.

Ami Hyūga is an average high school girl whose world comes crashing down when her brother Yu and his friend Takeshi Sugihara are killed by bullies, led by Sho Kimura.

Ami escapes and seeks shelter with Takeshi's parents, Suguru and Miki Sugihara, two kindly mechanics who fit her with a multi-barrelled machine gun prosthetic.

[3] The Japanese DVD from Nikkatsu came out January 23, 2009 as a 2 disc set including the short Shyness Machine Girl (hajiraiマシンガール, Hajirai mashin gāru).

[4][5] Tokyo Shock, the Media Blaster label which released the original US DVD, announced that they were bringing out a two-disc special titled The Machine Girl Remix on August 4, 2009.

[7] The film was rated 18 in countries such as Chile, Peru and Spain because of nonstop gore, bloody action sequences and a rape scene with suggested necrophiliac overtones.