Ichigeki Sacchū!! HoiHoi-san

In the near future, household pests have become highly resistant to all kinds of chemical pesticides. Naturally, the answer to this plague is miniature customizable robots, programmed to hunt down and destroy household pests using miniaturized weapons. A lonely young man named Aburatsubo has just purchased Mars Pharmaceuticals' latest model, ID-3 HoiHoi-san, a cute 10cm pink-haired girl in a maid dress made to serve his every whim, just so long as that whim is to ruthlessly gun down cockroaches....