This is not so much a secret spot as a word of advice. If you plan to travel around Japan, you need to get a JR Pass for rail travel. It costs ¥28,300 for a 7 day pass but is only available outside of the country. Once you get to Japan it can be exchanged (with passport) at any JR counter. It is probably available from other travel agents but this place is really cool as it has a Japanese supermarket, restaurant and gift shop as well as the travel agent.