Every other city has various circuits pertaining to all sorts of categories and this here is a list of the places in Bangalore where Japanese is taught.
Located at the always-buzzing Malleshwaram, I hear that SNRC is as wonderful as it seems to be, and that the teachers are very much competent. They have study from home Japanese packages, too!
The Department of Foreign Languages at Bangalore University is good is what I hear, but it'll be tough to get to contact them for legit information. They've Japanese diploma courses, too.
Japanese Language School is one institution I would personally recommend for I've done my N4 and N3 classes there. The teachers are very friendly and go out of their way to help students. The fees are by far the lowest compared to other Japanese classes in Bangalore perhaps.