I went here
Kudan Institute of Language & Culture, study Japanese in Japan, Japanese school in Tokyo, Tokyo, Japanese language school, Japanese, nihongo school,nihongo, kanji, hiragana, katakana, kudanshita, jimbo-cho, study Japanese in Tokyo and i was really happy with the teachers, the other students and the homestay. I booked here
Geos Kudan Institute of Japanese Language & Cultur Tokyo Discount Booking. Japanese Language School in Japan (i dont mean to advertise, i dont get anything if you book there!) because it seemed reasonable priced.
I did 5 weeks in the beginners class. I could already write Hiragana and Katakana so i choose the Conversation course wich worked really good for me. I can only recommend to learn a bit before you go, it can be quite fast sometimes.
I did the homestay and even so i was far outside i can only recommend it!
Have fun
Edit: oh yeah, if you are from Canada, UK, Germany, France, Australia, New zealand, Denmark or South Korea you can also get a working holiday Visa for 1 year.