There are a few things that foreigners in Japan should have on hand before they go out. Here is a short list of some useful items to keep with you at all times:

1. Passport and alien registration card
It is always best to keep your documents close by. You don't want to put yourself into a situation where you can't produce your documents for Japanese officials. You'll also need this information if you're planning to do certain things like purchase a cellphone.

2. Handkerchief or small washcloth
Many public restrooms in Japan don't offer paper towel or hand driers. Therefore, it's useful to keep something small to dry your hands with. Furthermore, in the summer as you swelter in the humidity and heat you may want something to blot your face with. It is a common sight in Japan to see women blot their faces with small handkerchiefs during the summer.

3. Tissues
In the same vein as the above paragraph, some public restrooms don't have toilet paper either. Keep a small packet of tissues with you to avoid embarrassment. Note that in many busy public places there are often people handing out free tissue packets with advertisements on them. Keep an eye out for them. It shouldn't be too hard to stock up if you're going to be in a big place like Tokyo or Osaka.

4. Hand sanitizer
Carrying a small bottle of hand sanitizer saves you a lot of rummaging in your purse with wet hands. Instead of dealing with handkerchiefs and the occasional lack of soap in a bathroom, just squeeze some of this on your hands and you're good to go.

5. Emergency money
It's common sense, but keep some extra yen tucked away somewhere on the off chance that you may need it. For example, you could use it for a taxi ride if you become lost or find yourself out later than midnight which is around when the trains stop running in some areas. Keep in mind that Japan is still a cash-based society so you'll use your cash more often than a credit card.

6. Comfortable slip-on shoes
You're probably going to do a lot more walking in Japan than you're used to so be sure to bring comfortable walking shoes. If you plan to go shopping, especially for clothing, it would be prudent to bring a pair of shoes that you can easily slip on or off. Generally, you are supposed to take off your shoes before you enter a dressing room in Japan and tying and untying your shoes can become a big hassle very quickly.

And if you're going to be in a big city and you are fashion conscious, you may want to pick out the most stylish slip-on shoes you can find. Both men and women in the urban areas of Japan are very fashionable. For girls, some cute low pumps would probably suffice in the winter whereas open-toed sandals and heels seem to reign in the summer.

7. Umbrella
An umbrella is always useful, just as in America. However, if you're visiting Japan in June and July then you're going to be treated to the country's rainy season. It doesn't normally rain all day but there's a high likelihood that you'll hit some wet weather at least once every day. And if you forget your umbrella, you can buy some cheap clear plastic umbrellas at nearly every convenience store for around 500 yen or $5.00.

However, it's probably best to buy a small collapsible umbrella that you can tuck away in a purse or backpack. You'll probably want your hands free to take pictures or buy any number of highly expensive Japanese items.

8. The address and phone number for your hotel/school in Japanese
Just in case, it is always best to carry around this information in case you get lost or just need a ride home. You may also be able to carry it around in English as many people in Japan do understand rudimentary English but to be on the safe side perhaps it is best to have it in both English and Japanese.

Of course all of the other common-sense items apply such as your camera, credit card, and any other items you normally take with you in America.