Being in Japan five years in total, I've witnessed my fair share of people being homesick. Most people manage it either by going home or by complaining. The people who can't get it out of their system just continue complaining. There is a mindset of "This country is so shit because..." or "Back home we don't do that."
Some people get lonely and try to get it out of their system by sleeping around. Somebody I know made numerous racist remarks about "J Sluts" but then slept her way around most of the guys in our social circle (not including me, though at the time I would have been keen enough). She claimed not to find Japanese guys attractive, which is fair enough, but why constantly moan about Japanese women as one homogeneous entity?
People seize the weirdest things to get worked up about as well. A former colleague bemoaned om-rice. "How can you trust a country," he said, tongue slightly in cheek, "that has restaurants dedicated to om-rice? It's only rice, tomato ketchup and egg. It'd be like having a beans on toast restaurant back home."
I'd be more than happy with beans on toast restaurants in England, I have to say. I'm not the world's biggest Om-Rice fan but I can't see it as anything to fixate upon.
In my darker moments, I get annoyed with: Celebrities in advertising; ATM charges; Ayumi Hamasaki; AKB48; political corruption.
But in England I had a higher quality of things to moan about: political corruption; living in a society with 1 security camera for every 12 people; difficult to find a job that pays well.
I can't moan about the country. Instead I let others do it for me. Or mutter about the slowest walkers in the world who congregate at Shinjuku station whenever I'm in a hurry.