Any foreign visitor who wishes to enter Japan must have a passport. That passport must be valid for the entire period of stay.

Nationals of many countries are eligible to enter Japan for a brief period without a visa for purposes of tourism. Which countries have the Visa Exemption and how long they may stay without a visa is detailed (in English) on the following Japan Ministry of Foreign Affairs website.
https://www.mofa.go.jp/j_info/visit/visa/short/novisa.html

Please carefully review whether your passport has a visa exemption, how long you may legally stay, and what rules are applicable to tourists from your country. Please be aware that the above list only applies to short-term stay for purposes of tourism. Extending the period of stay, living, working, or other commercial purposes will require other official visas.

Currency and Money Exchange

There is no limit on the amount of either foreign or local currency that may be brought into or taken out of Japan. However, if you transport any currencies, checks, securities, or other monies exceeding 1,000,000 yen worth in Japanese currency into or out of the country then you must declare it on a customs declaration form.

The unit of Japanese currency is the Yen. Coins are available in denominations of 1, 5, 10, 50, 100, and 500 yen and bank notes in denominations of 1,000, 2,000, 5,000 and 10,000 yen. 2,000 yen notes are rare, so for denominations less than 5,000, expect to receive 1,000-yen notes.

You can exchange your home country's currency for yen at foreign exchange banks and other authorized money exchangers. Currency exchange counters are found at international airports, and are usually open during normal office hours. The exchange rate fluctuates daily depending on the money market.

• World Currency Shop Exchange Rate

Public Phones

A direct overseas call can be made from some public telephones displaying an International and Domestic Telephone sign. Even though these phones are not as common as they once were, they can still be found near most large train stations. Coin currency or telephone cards (which can be purchased from convenience stores) can be used to make calls. When calling internationally, dial 001-010 - followed by the number.

Hotel Phones

Another option for emergency international calls is to ask at your hotel to used their phone. When using the hotel phone, first connect to the hotel operator before making your international call. Please be aware that the hotel will usually charge for use of their phone, which can be paid for with credit card at most locations.

Mobile Phone Use and Rental

You might be able to use your mobile phone in Japan's cell service area (depending on phone model and service provider), but doing so often involves additional roaming charges appearing on your phone bill. One better option is to rent a Japanese mobile phone, which can be done at most international Japan airports. For further information regarding cell phone use and mobile phone rental, please contact any of the following companies.

JAL ABC
SoftBank Global Rental

Free Wi-Fi

Many locations around Japan (airports, larger hotels, major train stations, others) will have free Wi-Fi available. Please be aware that, in many locations, the signal is usually only strong enough for brief texting, and may not be strong enough to sustain other data usage or internet browsing.

Sim Card and Pocket Wi-Fi Rental

Two cheap options for using your cell phone in Japan include renting a Japan SIM Card for your mobile phone or renting Pocket Wi-Fi to carry around Japan with you. Renting a Japan SIM Card means being able to use your phone to make calls or text anywhere in Japan, but please be aware that what SIM cards you can use depends on your phone model and the size of your current sim card. Connecting your mobile phone to the Pocket Wi-Fi means avoiding roaming charges from your service provider when texting or using smartphone applications like Maps over Wi-Fi. Phone calls can even be made over Wi-Fi from certain VOIP (Voice Over Internet Protocol) applications, such as WhatsApp, LINE, or Zoom, and some phones even have a Wi-Fi Calling option to enable in their Settings. And the Pocket Wi-Fi can be shared across multiple devices in a group of travelers. We recommend purchasing your Sim Card or Pocket Wi-Fi from Japan Wireless or Ninja WIFI, which have pickup counters in most international airports in Japan, and they can even deliver to your accommodation in Japan. Prices vary depending on how much bandwidth you need and how long you will use it for, as the cost is calculated by-the-day.

Ninja Wi-Fi
Japan Wireless

Facsimile and Computer Networking

Facsimile machines are available at most hotels. Ask the front desk or go to the hotel's business service center. Most hotels (especially Western-style hotels), will have Wi-Fi available for computer access.

Voltage Conversion and Appliance Use

The voltage used throughout Japan is uniformly 100 volts, A.C. There are two kinds of frequencies in use; 50 Hertz in eastern Japan and 60 Hertz in western Japan (including Nagoya, Kyoto, and Osaka). Because of this, a convertible type of electrical appliance (hair dryers, travel irons, and shavers, etc.) made for overseas travelers will be handy. If not, a step-down transformer or voltage converter will be useful.

Plug Types in Japan

The most common plug in Japan is the non-polarized, ungrounded 2-pin plug. There are no columnar-shaped plugs in Japan, and 3-pin plugs, though increasing in number in Western-style hotels, are still rare. Therefore, it advised to purchase a plug adapter beforehand, if you need it.

Winter (December - February)

The temperature rarely drops below 0°C in the plains along the Pacific coast during the wintertime. It is also quite dry and very often sunny. Central Japan and Northern Japan are highly reputable regions for winter sports. Southern Japan is comparatively mild and pleasant during the winter.

Suggested Clothing: Overcoats, sweaters, etc.