Aoi Mitaka works for "Night Hawk Taxi." She is a driver that also just so happens to provide sexual services to her passengers. As such, when a normal salary man wants to go do the redlight district he gets caught up in this particular service.

He doesn't know about this service but Aoi somehow knows a lot about the red light district and after making a flirty joke she switches the taxi into "night hawk mode" and then the counter starts.

The base price is 30,000 yen, each minute being 3,000 yen more. Since the man was gonna do this type of thing anyway he goes along with it. As every person would, with the time system he tries to get multiple nuts in to get his money worth. 

Of course, he goes on til morning and his money is sucked out of him exactly as Aoi's business plan wanted. One mention that she wants him to be his exclusive passenger and that the sex was good is all she needed to entice this poor soul to continue coming back.