A strange space woman sets up a dimensional field that separates a few abandoned blocks of Tokyo from the rest of the world. Inside, she has trapped the horrible and indestructible monster, Zeiram, along with two hapless power company workers. The workers provide distraction and comic relief, as Iria, the space hunter, kills the hideous monster. Well, that's what happens in the live-action movie which you may have seen dubbed on the sci-fi channel a few years ago. When I saw the same monster drawn as anime, I was shocked, and I had to know what was going on. Turns out that CJAS is showing IRIA: Zeiram the Animation; apparently, the live-action came first and someone thought they'd animate it. There's no manga and no more to it than the six episodes we have. Having seen both, I have to say that the only similarities are the bad guy and Iria. Nothing else is the same; no earth, no cool power company extras, and no strange dimensional fields.
Iria is an apprentice bounty hunter, meaning she cannot accept or perform a mission without the supervision of a licensed hunter. Her brother, Gren, has a license and taught her everything she knows; they're very close. They work for Bob; he's the go-between for them and governments or whoever else needs a bounty hunter's service. They have hover-devices on their vehicles that resemble coolie hats. I don't understand them any more than you will after seeing them; just nod and smile.
If you think Iria's armor (under that tarp she wears) has a suspicious resemblance to Karin's outfit in DNAČ, it's because the character designer for IRIA, Masakazu Katsura, is also the manga artist for DNAČ (as well as Video Girl Ai).