Wow, you seem pretty disappointed with your current position.
I hope things get better for you soon...
I think you will be starting to prepare too early if you want to teach in Japan next year in July. Unless of course you plan to teach at Uni or on the
JET program. Giving yourself 1 month prior to arriving in Japan is enough to find a teaching job. A lot can happen in 12 months, and schools really wont be interested in you if your arrival is 12 months later.
Can't you quit early and apologise to your school and help them find a replacement teacher? To spend the next 12 months somewhere where you don't want to be is going to be hell.
Nova is alright but you will be more of a number than anything else. They are huge in Japan, and your salary will be one of the lowest around. Other than that, they are fair and wont rip you off.
Japan is not as expensive as most seem. Checkout this thread regarding the
cost of living in Japan.
The JET program would be your best option. Some JETs have a blast getting top pay and benefits working only a light schedule with many paid holidays. If you can get on this program, then take it!