Tokyo and Osaka are very expensive. The apartment deposit is 3 or 4 times the rent. This is why it is hard to get set up in Japan. You can't just fly here, get an apartment and start searching. The housing is a real pain.
Most schools understand the situation.
I have such a job now, but I didn't get any help with housing. I have also been here for four years and that is what you will find in Japan. It is great. Japan is the most comfortable and modern country in Asia. It feels like the USA at times.