うさみみデリバリーズ!!

There is a city on a floating island. It's forbidden to construct high buildings there, so all the construction moves underground creating a vast automated infrastructure network.

Main character works for a courier company there. But one day rival courier appears stealing all the customers. Suddenly protagonist gets an offer to work for this new company with amazing rabbit girls that serve as the main attraction of the company. He can't really say "no" to such offer.