Where does one begin with Nova...
Ok, I've never personally worked there but I know about 10 people who have, and they unamiously agree that it is not one of the better teachings jobs they have had. None of those friends currently work there now. It is considered the McDonalds of teaching jobs in Japan. If you're going to teach English in Japan, I would come here and then look for a job. The only reason Nova (Aeon and Geos, and other large chains) look attractive is that they recruit overseas and set you up with everything before you get here. That is a good idea, but once people get here and start working, they realise there are better jobs out there with better pay and working conditions etc. Do a search, read the stories, you can do a lot better...
If in Tokyo, get the Japan Times newspaper on a Monday and you'll find a shitload of jobs. Check <a href="http://www.japantoday.com/" target="_blank">Japan Today</a> for job listings too. If you're not a complete moron (or "moran"), then you shouldn't have too much of a problem coming to Japan first and then finding a job. When I first got here (a while back yes) I found two jobs (one was teaching) and worked my ass off until I had enough cash to increase my options.
Ok, the English teaching racket has probably changed since I first came here (I no longer teach). The market is flooded with gaijin now, so prospective schools and employers can be a little more choosy. They probably want experience and some basic Japanese language skills. Also, they might not want to employ you if you are on a tourist visa. So going back to the Nova job- it's probably not a bad idea because then you'll have a job, work visa, AND a place to stay (ok, you'll be sharing with other Nova teachers), and you'll probably won't have a choice where you'll be sent to (Nova are nation wide). They will make you work hard and you'll probably have to work weekends, but so what? The contract might be 1 or 2 years (you'll have to check that), but it will give you enough time to sus out other options and when your contract expires- BAM! You're outa there and ready for the next best thing.
I know, it goes against everything I said about Nova, but there aren't too many other companies that recruit overseas unless you're a specialist in some other field. It won't kill you, but it will suck for a while. Hey, we've all worked a shitty job at least once in our lives to get to somewhere better haven't we?
Nova is owned by a credit loan company (if I recall correctly), so they are in it for the cash obviously and not famous for their amazing teaching techniques. I could go into it more but that's not really important now. Do a search and find out what else is out there, I've been out of the game for a while now so I'm not sure what's on offer right now. Read peoples blogs, those who are working as JET's or Nova teachers and find out what really goes on. A friends site:
www.avoidinglife.com, although he isn't in Tokyo (Aomori actually, northern Japan), it's a good insight to what a JET's life is really like.
Most of all- good luck! I've found Japan to be one of the most amazing experiences in my life, and that has been what has kept me here for so long I guess.