1. Bowing in Japan
Japanese often greets one another with a bow.
You can see different kind of bows, a bow that lower one's head below the waist, or a small bow that only moves one's neck just like nodding your head.
When you go to a shop in Japan, you will see it by all means. Bowing is deeply rooted in Japanese culture, even difficult problem can be resolved with a bow.
Also, by saying "Sumimasen" along with a small bow will open your way to get out of a train during rush hour. When people hear the word "Sumimasen" in the train, they will step aside and make a path for you to exit, some people even give you a small bow after they had stepped aside.
Try not to say "Excuse me" when you are in Japan.
Most Japanese know the meaning of this word, but in a real world situation they will be frightened. They usually think "Are you talking to me?", "What did I do?" or "What should I do now?".
2. Paying for things or services
How does the store's staff give you a bag of products to you in your home country?
Recently I noticed that when I go to a convenience store in Japan, after paying the products the staff gives me the bag while looking at me and touch my hand.
If this also happened to you, let's not get angry. It doesn't mean the staff had a crash on you, it's just part of the service. I don't really know why they need to do that.
Also, I think it is written in many travel guides that "tipping is not required" in Japan.Even if you go to an upscale restaurant, you don't need to pay tips. If you take a look at the receipt, you may notice that the service charge is included.
This culture background lead to many Japanese forget to pay tips while traveling aboard.
3. Finish your meal without leftover
I think of this situation, when eating with a Japanese friend.
Since the old days, ordinary Japanese households have been trained to finish their meal without leftover. Also, there is a Japanese saying that "Finishing a child's leftover is parents' responsibility".
In other countries, it is okay to have leftover if you are full. In Japan, if you have leftover, it is considered a waste of food and unacceptable. People will question your personality and think there is a problem with your family.
Have you ever heard the phrase "Mottainai", this phrase was created after postwar Japan because there was a problem with a shortage of food. Current generation's inherited the concept not to waste food from their grandparents. In addition, the Japanese are trained to finish their meal even if they dislike it.
There is also an impression that eating food that you like is natural and avoiding food you dislike is self-indulgence.
The concept of finishing your meal without any leftover is not in every culture, it maybe hard for other people to understand.
If you ask me "Why should I eat it, if I hate it?"
I will say you missed the point, it is about "not to waste" any food. That is Japanese and Japanese culture.
When you eat Japanese food for the first time with your Japanese friend, it is better to tell them how much you would like to eat, otherwise they may concern about the waste of food and only order a small portion for you.
4. Language barrier
Japanese who can speak English either had experience living in English speaking country or wanting to learn English.
For example, you are walking on the street and get lost, you try to get direction from a stranger near by using a phrase you have learned - "XX wa doko desu ka?", that stranger explain the direction to you in Japanese quickly, At the end you don't really understand what this stranger say and just want to end the conversation by saying "Arigato" without getting the direction you needed.
Most Japanese who don't speak English fluently usually worry about making mistakes when they speak English, so even if they want to help it will be difficult.
Of course there are some very kind people who will take care of strangers until they arrived to their destination, but you don't see them very often.
Yet, they are willing to help you, you don't have to feel unpleasant.
Overcome the language barrier is more difficult than you think.
Most important things in the conversation are the conjugation. If you make a mistake, it is hard to understand what are you trying to say.
Example:I'll go to the school with A.
1. Watashi gakkou ni ikimasu. A to issyo ni.
2. Watashi ha gakkou ni A to issyo ni ikimashita.
3. Watashi ha A to issyo ni gakkou he ikimasu.
Which do you think is the correct?
Certainly, Japanese face the same problem when they speak English too, learning Japanese is very hard as well.
5. Are you frustrated by consecutive questions?
When you come travel to Japan, and even if you've been living in Japan, people often ask you the same question:
"where are you from?"
"where do you live?"
"how old are you?"
"how are you?"
You might be tired of those questions, but I'm sorry because I asked those questions too.
This is a problem of language skill. In general, the Japanese start to learn English in junior high school, from text books or tv shows. Those questions are proposed as the basic conversation.
We don't learn anything more difficult than that except people who have enthusiastic for studying English. Since those are the only sentence most Japanese know, even if we want to talk to you we could only ask those sentences. Since English is not widespread in Japan.
As you can see, there are many spelling or grammar mistake for signs on the street and also on TV shows, so now you will understand why.