In my case, I never had any real culture shock when I went to Japan. I'd say I stayed firmly in the 'honeymoon phase' for the full two years I was there. I loved my job, my co-workers, my everyday life, the area I lived in, the new experiences I was having, the independence, the sights, the trips... Even when I decided to leave, I felt like I hadn't had my fill of Japanese life. Given that, I was probably a prime candidate for reverse culture shock.
I'm sure reverse culture shock has many reasons and manifestations, but in my case, there were three key factors:
Then you return to your own country, and have to realise that you are the only one of your friends who is interested in Japanese things. Sure, your friends might like to hear some of your stories, have a quick look at some photos, etc, but the key word is 'some'. I had to watch myself, that I didn't begin too many sentences with the words 'In Japan...'
I think a lot of returning expats, after extensive travel and mingling with other travellers, also have a feeling that their own society is a bit parochial, not interested in the world outside. Really, I think that's true of every country - everyone is most preoccupied with themselves - but it is more striking after going away and coming back. You feel that your worldview has changed, so it's more noticeable when others' haven't.
Now, I highly value the deeper friendships I have here in Australia - where I know I could go away, and come back, and go away, and come back, and they would still be my friends. But I also found that being away from everything familiar made me act in different ways and experience different things than I otherwise would have.
Indeed, I almost felt like a different person altogether in Japan. I think Japan suited my personality, because I felt very relaxed and confident there. I rarely experienced insecurity, doubt, ennui, gloominess. A few moments of loneliness in the early months, before I made friends, but in general I felt great, like I had changed.
But when I came back to Australia, I felt like I reverted to the person I was before I left. I'd become more nervous about things, less inclined to be active, more worried about my future. Naturally, this made me wish, all the more, that I were still in Japan.
I was aware that there were things that, while not a problem for me as a temporary resident, could be tough about life in Japan if I were to settle there. And so I never exactly thought of Japan as 'home'.
But when I came back to Australia, I didn't feel like Australia was 'home' either. Rather, I felt that I was yearning to get away again, experience the freedom and novelty again. I will soon do this, but now I have a new concern - where will it end? Will I keep going to new country after new country, looking for novelty, never settling, never considering anywhere my 'home'? And if I do go gallivanting forever, is this a problem?
I feel like I've opened a bit of a Pandora's Box from the time I first left my homeland. Before I left, I was perfectly contented here, but now...?
Anyway, these have been the basics of my own personal culture shock. Just thought I'd share this more personal post lest others have the same experience.
I found this good blog post: How to Survive Reverse Culture Shock. I enjoyed reading some of the readers' comments - it seems to be a fairly common phenomenon.