There is a hospital in town that handles deliveries and prenatal care. The Doctor and many nurses speak English, or at least enough to communicate. They do the 3-D ultrasound at every visit.
The doctors out in town are very competent and there is a great NICU at the main hospital (just in case). They do epidurals and circumcisions (if you want either). The only out of pocket cost for in town delivery is about 50 dollars a day for a private room, and that is optional. Dad can stay in the private room, and in the delivery and labor room, as well.
The doctors work 6 days, so you can get Saturday appointments!
If you are high risk or simply uncomfortable with the thought of delivering out in town, you can opt to deliver at US Naval Hospital Yokosuka, which is several hours away by train. Iwakuni's base clinic would provide most of the care throughout the pregnancy, and you would be sent to Yokosuka around 36 weeks to stay until delivery.
(Images: Base Medical Facility, Ambulances.)