Japan is a country with a very low crime rate and it is very uncommon to become a victim of pickpocketing, theft or agression.
However, it is always advisable to keep an eye on your personal belongings during your stay.
In Japan you will find parallel A type plates and it is necessary to buy an adaptator that you could easily find in mini-shops called "Konbini". Please note that some electrical devices couldn't be suitable with Japan voltage (which is operated a voltage range of 100 to 130 volts) so be sure to check the voltage range of your devices before leaving.
It may be better to check your call rates from international communications (especially on the Internet) that could be extremely expensive. If so, you could rent a phone for the duration of your stay at the airports.
Although well-developed in most of Japan, please note that you may not have access to Wifi in some isolated places in the Japanese countryside.
Japan has a temperate climate. Winters are cold and dry, spring has a mild climate, summer is hot and humid and autumn is quite rainy. However, Japan is a country extending widely from north to south and the climate varies significantly according to the latitude. Similar temperatures are found in the Scandinavian countries on the island of Hokkaido in the extreme north during winter and on the other hand, a tropical climate if one goes to the Okinawa archipelago in the extreme south. Japan being also a mountainous country, the climate could be variable according to the altitude. From the end of summer to the beginning of autumn, Japan is hit by typhoons announced in advance by weather stations. The month of June, preceding the hot and humid summer, is accompanied by a broad rainy season (Tsuyu in Japanese).
In Japan, it is not usual to tip. However, if you wish, slip money into an envelope discreetly before giving it to the person who will be grateful.