There was a time when you had to speak Japanese to travel in Japan and you needed a fat wallet. Those days have gone. The Japanese Yen is no longer highly priced and enough people speak English for you to be able to get around. However, bear in mind that the Japanese are not brilliant linguists. Like many English speakers, they find it difficult to speak any language except their own.
Getting around is easy. The country has a superb rail and road system. You can take a train, travel by bus or hire a car. If you plan to take domestic flights see if these can be purchased as part of your international air ticket, as this can save money.
Car hire prices are about the same as in most developed countries. My wife speaks fluent Japanese and we usually take a train to where we are going to start our tour. We leave the railway station and shop around in the car hire places that are to be found near most big railway stations.
If you don't speak Japanese, use the car hire counters at the airport because this is where you will find the English speakers. Then take a train to where you want to pick up the car. An international driving licence will be needed together with your national licence.
The Japanese drive on the left and use the same international road signs as in most countries. Drinking and driving is strictly prohibited but there is a relaxed attitude towards speed limits, which are set low and not rigorously enforced. I set my speed to match that of other road users. On the whole, the standard of driving is good.
If you are planning to travel by train, take advantage of the generous rail passes that are available to visitors from overseas. Take a look at www.jrpass.com and shop around to see what is the best deal for you. At the time of writing (Jan 2016) rail passes (for foreigners) can only be purchased from outside Japan. My Japanese friends wish they could buy them on such favourable terms.
Money: Major international bankcards (Visa, MasterCard etc.) are accepted almost everywhere for purchases. The problem comes when you try to withdraw money from a cash machine (ATM). Hardly any of the banks accept non-Japanese bankcards. I always take some Japanese currency with me. When I want to withdraw cash, from an ATM, I go to a post office in a major centre. These are run by the Japanese Government and have ATMs that accept international cards.