Japanese grocery products

not sure about FRESH miso paste
but you can get original japanese miso soup and other Japanese products in the Chinese supermarket close to the Bourse

Go to a Japanese store - Shilla in Auderghem is pretty good and has lots of different kinds of fresh miso.

http://en.yelp.be/biz/shilla-auderghem

Japanese supermarket on chee de Vleurgat, just a couple of steps from
Ave. Louise.