Hi guys.. I was fortunate enough to spend the best part of a month in Japan, working at the football World Cup in 2002 and its a fantastic country to visit. It would take me forever and a day to describe it all here so I'll try to dip in and out as time and memory permit.
But first off, don't rule anything out. Tokyo is the obvious and good place to start, an incredible city with lots to see and do, from the shops to the sightseeing, the mini Eiffel Tower and Statue of Liberty.. we spent a pleasant afternoon down by the latter on Tokyo Bay. There's also Disney Land and Disney Sea, the latter being the more interesting if you are so inclined.The best way to see Japan is by train and I am sure you know the reputation for comfort and punctuality they enjoy. An experience in themselves. Back then we were able to buy a rail pass in advance which saved us hundreds of pounds, so check if these are still available.
Outside Tokyo, hop off the train and stop over at places like Kyoto, again its reputation goes before it; likewise Hiroshima. Do not go to Japan without visiting this incredible city, it is jiving, and the history and realisation you get from being on the ground where it happened will take your breath away.
Mt Fujiama has to be on any itinerary and we also spent a pleasant overnight in a seaside city called Fukuoka though that was before the tsunami.
We also flew up to Sappora for a game but there isn't really much to see so save your air fare for day to day living. Japan was expensive in some ways, chiefly alcohol and taxis, and similar to the UK in others, eating out and shopping for clothes etc; you will find the electrical goods both cheaper and ahead of what we have here. Or use the money to fly to one of the Pacific islands, we went to Okinawa and were overwhelmed by both the hospitality, the beauty and the history.
Again, the airfares were cheaper when purchased outside the country, prior to arrival.
The people everywhere were fantastic, very friendly, if reserved; always helpful and extremely honest.
Crime against the person is practically non-existent, though there have been some highly publicised extreme cases in recent years. Just take care there, the way you would here, and you'll be alright.
It is actually like being in two different countries; Tokyo being in many ways almost American-ised and the more traditional Japan existing outside the capital. Hope that helps for now... be back if and when I think of more.