I have posted something to this school before
Kudan Institute of Japanese Language & Culture Co. Tokyo Discount Booking. Japanese Language School in Japan
i stayed in Japan for a year and i spent 5 weeks in this language school. I had only basic knowledge but the school worked out fine. Teachers are good, the fee is ok and my homestay was awesome (tough a bit outside).
If you don´t need japanese for school or work i´d recommend a half day conversation course with a homestay. With this you´ll go to school 4 hours a day and can hang out with all cultures visiting this school afterwards and explore Tokyo.
I did learn alot and i think the teachers fit the language levels and are good.
Enjoy
Firebird