There are some small, furnished serviced apartments owned by Japanese companies who specialize in such things and have them throughout Japan.
They are not a bad option for people who are only in Japan for 6 months or a year because we don't need to buy furniture and so on.
Be careful though, as they usually require about a months rent as "key money" which is not refundable (standard in Japan), as well as a substantial bond.
Despite at least one of them advertising on the net that a Japanese garantor is not required - that is often a misrepresentation too and one is often required (unless the place will be rented by your employer - which then ties you to that employer!)

Leopalace is a big company in Japan that has serviced apartments.
They advertise that they rent to foreigners and that key money and guarantor are not required.
HOWEVER, when I fronted up at one of their offices I was told that BOTH were required.
I pointed out that their website says differently but they just brushed me off.
As a result, I do not trust them and would not use them.

I have applied to teach through Interac and they normally advise going with Leoplace.
Some accommodation places prefer to only deal with companies etc rather then individuals but nearly all places require key money and returnable deposit.

dont forget that these sites are also for the japanese and so because they are normally more trust worthy and respectful of the places they rent it maybe them who dont need to pay key money etc
This may seem slightly unfair and misleading but you have past westerners to thank for that

Actually I talked to Roger about this a few months ago..
Leopalace's site for foreigners said (in English) no key money and no guarantor was required for foreigners.. but it turned out that it was not true.

And the branch I went to treated me like shit

But you are right when you say it was previous foreigners to blame.

Oh dear that doesnt sound like good news...i am hoping to hear from interac before xmas if they are offering me a job and then coming in march and they get most of the accommodation from Leoplace
I think though, interac sort most of it out and just expect us to give them the money...i hope that is the case...
it would be nice not having to pay key money but i am expecting to pay it so thats included in my sums of money i need to save...
I think i worked out i would need ?3000 for the first 2 months before i get paid for teaching - this would pay for 2 months rent, the deposit, key money and money to live off...i think thats ?500,000

That sounds like it might be enough

Don't worry, you will survive it all