If you want to learn Japanese in a comfortable, friendly environment, J’s Language school in Ebisu is a great choice. I’ve been studying Japaneses with J’s Language school for about 3 months total from 2013 to 2015 whenever I’m in Japan, and I’ve loved it. The quality of teaching is great, the teachers are fantastic, and there is emphasis on speaking only Japanese in class as much as possible. Also, the teachers don’t only teach right out of the book, but will also emphasize speaking street Japanese in everyday life. They use the Minna No Nihongo book, which is superb to any other book I’ve seen. The hours are convenient and flexible, and the location is great. If you’re interested in studying for the JLPT, they are able to help you with that as well. I warmly recommend J’s Language school!