It is quite rare to come across such a specialized store: Kado sells liquorice, nothing but liquorice. 

Liquorice in rolls, in sticks, liquorice spirits, liquorice powder, covered in chocolate, sweet, salty, tangy, sugar-free, liquorice Salmiakki and its unexplainable ammonium chloride taste – nordic countries are crazy about it – and little metallic boxes that will make you want to carry your liquorice with you at all times. 

From Iceland to Italy through all Scandinavian countries, more than 400 varieties can be found in the Kreuzberg shop : if you dare not buy something, you should at least try the house mix which blends all of them (3,20€), 200 grammes of russian roulette for your mouth. 

Graefestrasse 20 / 10967 Berlin
http://www.kado.de/