I´ve been living in japan for a few years and there are still many new things which I learn and experience every day. Living in a different culture often means many differences to your own country but also many new experiences.
First off it is very recommended to follow the rules in Japan. Walking on the correct side of the escalator, standing in the line of subway or just about the right greetings with co-workers. Especially in big cities where many people are living together it is important to follow the rules, otherwise everything will end in a big mess. If you don´t know what is right, just check what the others are doing and do the same.
When you are just arriving in Japan and you don´t know anybody it is very important to meet new people and make connections at your workplace and also for your private life. Especially in Japan, good connections can open you many doors. Also it is very important for the mental health, otherwise you will have depression very soon.
3. Be always kind
Be always kind to the people around you. Don´t show that you are in a bad mood or have an other opinion. In Japan it is very rude to show very direct your opinion. Try to show always your positive side and don´t be negative. The people around you will appreciate that.
To travel around Japan is very easy and safe. I used to travel often alone around the country and never felt unsafe. Especially people in the countryside are very kind and helpful and the very good transportation system ((by Bus, Car, Train, Airplane, Ferry)) makes it very easy to travel around. Even if you can not understand Japanese you will always find somebody who can help you and sometimes they even guide you to your destination.
5. You will always be the foreigner
Even living a long time in Japan, people will always see you as a foreigner. It happens very often, that people talk to you in English even when you speak Japanese to them. This can be very frustrating but never give up! Also in the countryside it is rare to see foreigners, that´s why people are very curious and stare at you or will ask you many questions.
6. Public holidays
Japan has many amazing holidays and festivals. I really love those days. There is really a day for everything! Like the day of sport or the day of mountain. But usually nobody celebrates these days, moreover people rest at home or enjoy a day off. The opposite are festivals, for example tanabata (star festival) or hinamatsuri (girls/dolls festival), which are big events with many traditions. Try out as many events as you can, it is a lot of fun!
7. Zentral heating & Air Conditioner
There is no central heating in Japan except in the northern parts. So, please take care to always stay warm with many clothes, blankets and other heating supplies like heating carpet, kotatsu (table over an electric heater) or heattech clothes. Japan can be very cold in winter and the air is very dry. On the other side in summer it is very hot but all buildings and transportation have air conditioner but they are often too cold, so it is better to always carry a sweater with you.
The first time I came to Japan, I was very confused to see little kids staying up late outside and it seems to be so normal. Especially kids who already attend school have to study a lot in Japan and often go to afterschools or cram schools which will end sometimes very late in the evening. Usually school and work starts late (around 9 h) in Japan, comparing to my country, that means that everything also ends late.
9. Amazing Delivery Service
Since living in Japan I really love the post service here. You will always get your packages on time. They even come late in the evening, if you ask them. It is very great that you can let packages deliver for a specific time without paying an extra fee. Even if you need to send something inside Japan, they will come to your house and pick up the package without any extra cost. For sending overseas you can use one of the 24 h post offices which you can find in many areas.
Number ten should be also number one. The most important thing is to learn the language. It is very hard to live in another country without speaking the language. Without Japanese it is very difficult to find a good job, rent an apartment or just open a bank account. You will need Japanese all the time in your daily life. English is not that popular and most of the people cannot understand or speak it.