What are the top causes of 'culture shock' in Japan? Besides the fact that you might have suddenly become a racial minority, in my experience the top causes of culture shock in Japan are, in no particular order: language, transportation, clothing, and food.
Well, this is really no surprise. Has anyone experienced the social anxiety of speaking with strangers at a party? Maximize this by 128.4 times and you will get an idea of how terrifying speaking to someone in a foreign country can be for you, a student of the language, who may have never set foot in any foreign country at all. There are some people who have no trace of the social anxiety mentioned above, and there are plenty of people like that studying in Japan, too, who, no matter how much Japanese they may currently be able to speak, just have a confidence and a way of communicating that breaks through language barriers. If you are not one of these people, you may find that your Japanese skills are just not up to par for you to communicate freely. Or, they may be up to par but you just can't seem to interact properly. Upon entering Japan, are you feeling a bit like Douglass Adams in Innsbruck, Austria? Take a breath and relax. There's a way to combat this.
You might say, "The only way to get better at speaking is to speak, but how do I speak if I can't speak? I don't understand! Graougaouaowoewugohogheeeee!"
Honestly, you aren't going to like it if you're shy, or the type that can't stand to do anything imperfectly, but here's what you have to do: Speak. Be misunderstood. Try again. You have to realize, you aren't going to get any better if you don't try. Don't feel like you have to speak perfectly at your first go, because you probably won't be able to, and it will frustrate you. Don't feel like you have to be the life of the party and gabber to everyone, because that could scare you, and you'll end up saying nothing. The end result is that you'll avoid Japanese at all costs, and at the end of it, when you return home, you'll have little to show in experience and in language ability. You just have to start with small goals. It's the equivalent of pole-vaulting over a wall, or taking some steps up to the top. If you can pole-vault, by all means, do. But if you're going to end up smacking your face on the wall, it would be better to just take the stairs, even if it's a bit slower.
To start, just put yourself in situations where people are speaking Japanese, and might speak to you. This should be easy, since you're in Japan. Go to a restaurant. Go to a store. Join a sports club. Once you're there, make a small goal. I will talk to one person. I will ask one simple question. I will order one dinner. Maybe all you can bring yourself to do is point, say please, and say thank you. Well, that's something. The important thing is that you're putting yourself where the language will reach you, and that's helping you learn a bit right there. Put yourself out there, and don't beat yourself up when you can't say something as fluently or perfectly as you could say it in your native language.You WILL learn something. Don't let this language shock turn into a fear of Japanese.
Being someone who doesn't own a car, this shock didn't hit me too badly, but for those who have the freedom of personal vehicle ownership, Japan may drive you a little crazy. The train systems, especially in large cities, are virtually always on time, but you might not like to wait at all. And that they usually all shut down around midnight? How are you supposed to get home from parties? Is there such thing as a party that ends before midnight? Whyyyyyyyy?!
Yes, you may miss that freedom. But really, it's not that bad. I have no background riding trains, except in Japan, so I found it conversely very liberating. I can go anywhere, at (almost) anytime! You may have to wait for a train a couple minutes, and organize your day around the schedule, but the trains run so well and so often, it's hardly a problem. You might not even have to pay for your gratuitous travel if it's included in your travel pass! Plus, you can always get a bike, too; Japan is very bike-friendly.
The thing about trains stopping at around midnight is kind of a pain, though, if you are a homestay or have a curfew at your dorm. Is your homestay not close to a station? You might have to ride your bike home at o'dark thirty in the morning, after having run for the station to catch the last train of the evening. Is it too far to bike? Then you need to be home before the last bus stops running, which might be even earlier than the last train. You've gotta get on a train and get on that bus or risk being left without a place to sleep. No parties for you, unless they end at 10. Really, though, sometimes you just want to drink (if you are 20 or over) and have a good time, and riding a bike home is a no go and missing the last train can't be avoided. In that case, you have many alternatives, though it may take some money. You can stay in a manga cafe with capsule rooms if you want to sleep, or in a karaoke bar if you want to party til the morning. Maybe you have a friend homestaying nearby? If you set it up ahead of time, your friend's host family may allow you to stay over. See? This is an easy shock to get over.
By clothing I really mean body image. As a foreigner you may be markedly bigger than the general Japanese population. This may only apply to guys in the shoe department, where tennis shoes may have to be specially ordered if you're very tall. If you're a girl though, you might find that not only are you tall with "large large" size feet, but all of the girls in Japan are five dress sizes smaller. You'll find all kinds of cute/sexy/kick-ass clothes and cute/sexy/kick-ass shoes that you want to buy, but none of them fit you. This can lead to some body image problems. If you're like me, you combat your negative issues with copious amounts of food, perhaps to prove that you don't care one whit for body image and diets. But this will just make you feel worse about yourself! You might feel pressured to eat less and less, but you'll miss out on a lot of fun and interesting opportunities, like nomikai with friends, and on a lot of new foods if you're obsessed with getting thin. This won't make you feel any better, either. You may get thin enough but by that time you won't feel it's thin enough. Don't get into any unhealthy behaviours, ladies. If you are heavy, and joining a sports club or taking a Japanese-style diet that's heavy on veggies can help you get healthier, go for it. But many girls studying in Japan are perfectly fine as they are, and seeing hundreds of tiny Japanese girls at college, combined with the fact that their kimono is a size L, just sparks something crazy in them. Many larger chain stores have a larger variety of sizes of clothes and shoes, in the same or similar styles, so don't fret too much about it. Stay active, be moderate in your appetite (most of the time; there's something to be said for moments of excess) and ENJOY YOURSELF. This is a shock that is a completely unnecessary source of strife and stress.
I believe you should have an open mind and try everything at least once, but for those of you with severe allergies or aversions, do not panic. (You may be placed in a very traditional household in the country, with no restaurant for miles, which serves fishy soups and rice and all manners of things you would never eat or never eat daily at least, but really the chances are slim, especially if you are honest with yourself about what you can and can't handle. Can you really not imagine eating rice everyday? Trying fish for once? If so, make sure you say so in your study abroad applications. If you are allergic to certain things or are vegetarian, for example, you'll definitely find that the program will work to make sure you are served things that you can eat when you travel.) Anyway, you'll probably be somewhere near a city, and the cities of Japan are full of restaurants and supermarkets. You can live on ramen and burgers and bread for your entire stay if you really want. Some cities even have Costcos, full of foreign food products. Sure, you may find 'strange' things like burgers with eggs on them, or go into a 'Mexican food' restaurant and see cinnamon sugar curly fries on the menu, but really, there's quite a variety of things to eat in Japan. It's a modern country after all! It's not as if every restaurant and household serves raw fish on rice every day of the week. (Sushi is actually very, very rarely served in a private home. Rice, though, can be honestly seen at every meal.) Don't allow yourself to get homesick or frustrated by your inability to get any of that home comfort food. Accept that some things will be different from what you're used to, and politely avoid the things you know you won't be able to handle. You should try very hard to sample everything you can though!