Meeting People in Japan
Whether you're planning to come to Japan or have already arrived, the more people you know here the easier it will be to settle in. You may be looking to expand your social circle, get into a sport or hobby, even find a girlfriend or boyfriend. All of the above are easier if you speak the language but lots of people manage to get by without it. There are plenty of clubs, associations and parties catering to foreigners, mainly English-speaking ones, and there's no end of Japanese who are keen to hook up with you - for all kinds of reasons. Of course if you're the super-sociable type, just being out and about enjoying the multitude of distractions that Japan has to offer, during daylight hours and after dark, will probably be enough for you to meet lots of people. Otherwise, you may want to take advantage of some of the services set up by those of a more enterprising nature.
Most of the big cities have at least one area where the nightlife is particularly "hot." But none can compare to Tokyo's Roppongi district. Originally home to many of the ex-patriate community working at embassies and foreign companies in the area, it became more of a "meat market" as the English teaching hordes arrived in the 80s. The more popular bars and clubs are filled to bursting on weekend nights and many party through to the following morning. Basically a great place for the young, free and single but "relationships" tend to be, how can I put this - fleeting. As the number of westerners has grown over the years, more and more of them have opened bars and restaurants which have become gathering places for fellow "gaijin" and japanese who like to hang out in a more international atmosphere. One example is the growing number of Irish pubs that have sprouted up all over the country, especially in and around Tokyo.
The internet is, of course, first and foremost a place to find or share information. But it's also a good place to find people. Recent years have seen an explosion in "de-ai kei" (encounter) sites for Japanese, with many of them oriented to mobile phone users. They have developed a bad reputation following a series of murder cases where the people involved first met online. There is also a tendency for people to be less than honest about all sorts of things when online - but you probably knew that already!
There are several penpal and personals sites that cater to Japanese people who want to meet or correspond with foreigners in English (and presumably in other languages). The various city-guide magazines usually have classifieds, with lots of ads in the 'friends', 'teach me' or 'women looking for men' kind of categories. If you contact someone, you shouldn't have too-high expectations of the level of English or the quality of the content, though. You can expect lots of broken English questions about your hobbies, your country and what you look like. Also, people seem to more laid back, or perhaps I should say less reliable, when it comes to email correspondence. Things might seem to be going quite well and then suddenly just stop. And it goes without saying that you should as honest as possible about your intentions.
There are also sites that cater specifically to dating and marriage. I don't know how shady these companies are in general but I guess if you're serious, you might decide it's worth taking a chance.
In the real world there is enough of a foreign population in Japan these days for just about every sport or common hobby to be accessible in English. There are clubs for things as diverse as softball rugby, martial arts dojos, flower arrangement, amateur radio, swing dance and foot fetishists. Most countries have their own society or network, many of which are online, too. There's just too much for me to try and list them all here and keep them updated. Your best bet is to check the free classified magazines that are circulated in most big cities. Some clubs as well as the magazines themselves organize regular international parties.
And of course there is always good old daily life. Japanese people, in the cities anyway, have become much more used to seeing foreigners. The result can be good or bad depending on how you look at it; people are less likely to run away or try to avoid you if you approach them but, strangely enough, they are also less likely to strike up a conversation with you, unless they're drunk! For the many people who come to Japan to teach English, there is regular contact with students and staff. If the students are adults and the school doesn't specifically prohibit socializing with them (as NOVA does did, for example), you can expect them to be very happy to go out drinking with you.
A relationship with a Japanese person, or anyone else for that matter, will have its ups and downs. If it's a Japanese person, there may be cultural and/or language issues that crop up now and again.