Fight Ippatsu! Juuden-chan!!, Asobi ni Iku yo! Recommendations
Fan-service and sci-fi action. If you're looking for both of these genre, then these two series might be something worth checking out.
The lucky or maybe unlucky protagonist gets into situations involving the girls and later forms bonds with them through the series. It does have a story plot though so keep an eye on that. There's also comedy, drama, and action. And here it is again: fan-service.