lurkerwithout | The Machine Girl

Teenage girl Ami's little brother and his friend are murdered by the son of a Yakuza boss. When the police label it a suicide Ami goes forth to find vengeance. But the Yakuza boss and his family capture her and chop off her arm while torturing her. But Ami escapes and is taken in by the mechanic family of her brother's friend. They nurse her back to health, help her train and build her a machine gun replacement arm. Just in time to face the Son of Yakuza boss and his trio of track suited ninjas. After that it gets slightly weird...

Also people don't just die. The explode in fountains of high pressure blood and/or gore. Or are cut to pieces of bad cgi f/x...