Short term language school

Me and my cousin are both applying for the holiday working visa when I get back to Canada (currently in Japan for 3 months as of right now). I am 20 and my cousin is 18. He doesn't know any Japanese and I know a little, but not enough to get by everyday with. So with a holiday working visa it is for 12 months.
with that said we were looking for a 1 month or 2 month course to know some Japanese while we're here for the remaining 10 months.
Does anyone have a good experience with some short term language schools in Tokyo or Osaka?
Thanks

What time of the year do you plan to come to Japan? I am asking because they tend to have short term courses during breaks such as summer holidays.

Another thing: I believe you need to have lived in your country of citizenship for some months before you can apply, so be careful with the timing.

I am attending Yamasa School in March. They offer flexible studying times from 1 week+ and you can choose when you want to start. So far my dealings with them via email have been superb and very professional. Only thing is they are located in Okasaki, which is near Nagoya, for me this isn't a problem as I am going there just to study, others may find it a bit remote compared to Tokyo or Osaka.