Shinkansen are no ordinary trains. Nicknamed 'bullet trains' for good reason, JR's shinkansen are the fastest and best-known services in Japan, and just seeing one zip past is impressive. If you are travelling long distances in Japan and need to get around the country, they are much better than airplanes.
Not only can you simply turn up and buy a ticket on the day (usually with the choice of reserved or non-reserved seating), but you don't have to waste time going through an airport, and will most likely get to your destination quicker as a result. What's more, shinkansen are smooth and quiet, with far more legroom and much comfier chairs than I've ever experienced on a flight. Riding the shinkansen is so relaxing you'll be tempted to go further than you had planned, just to stay on the train. It's a matter of simply sitting back and enjoying the ride, while watching the Japanese countryside stream by outside your window.
To ride the shinkansen can, of course, be expensive, but there are a range of passes and discount tickets that can make the shinkansen really worth your while: an all-encompassing Japan Rail Pass is perfect for those intending to do extensive travel within Japan, and regional passes, such as the JR East Pass and the JR West San-Yō Area Pass, are intended for those travelling in more specific areas.
During peak periods, such as New Year, it's a good idea to reserve a ticket in advance, as shinkansen travel can get very popular. There are both regular and Green Car carriages on shinkansen (as there are on most long-distance JR trains), with seating being slightly more spacious in Green Car carriages. You can also request to be put in one of the smoking cars on each train. If you're travelling for a number of hours and have forgotten to pick up a bento box from the shinkansen station you departed from, you'll be grateful to hear that you can buy food and drinks on the shinkansen themselves.
If you have a need for speed, then riding the bullet is the perfect way to reach your destination. A Hayabusa series shinkansen can get you all the way from Tokyo to Shin-Aomori, at the northern-most tip of Tohoku, in just a little over three hours.
Zip zip zip.