Most of sake are made of rice , malted rice, water and adding alcohol. However, Jyunmai-syu does not contain adding Sake. Thus, this sake has calm and deep rice taste.
There are 2 types within Junmai-syu. One is jyunmai-Ginjosyu(純米吟醸酒). Its rice grain should be polished more than 40%. It is because of strach and protein. There are a lot of protein on surface of rice grain which makes sake’s taśmę rough. In cotrast, there are strach inside of rice grain. It makes sake’s taste refreshing. Also, Jyunmai ginjiosyu takes more time during fermentation process because it is low temperature and fermentation goes slowly that other type of Sake, which makes sake’s taste gentle. There is a The up-graded jyunmai-ginjosyu, which is called jyunmai- daiginjyo (純米大吟醸). Sake makers polish more than 50% of rice grain to use and it makes taste very refreshing!!
Also, there is Tokubetsu- jyunmaisyu (特別純米酒). “Tokubetsu” means special. It’s process should be unique as rice grain is local one , using different equipment than others, it has additional process to make sake and so on. There are various ways to make sake and it is not certainly categorized. If you travel in Japan and find some local shops, you might get Tokubetsu-jyunmaisyu from the local. It would make your traveling special.
[How to taste jyunmai syu?]
To taste jyunmai-syu, I would recommend you to drink it with room temperature. Jyumai syu has calm and deep taste and you can feel it with room temperature. You also can heat up it around 35-40degrees, which is called Hitohada-kan(人肌燗). You can sense more flavor from the cup.
[Marriage with cuisine]
To drink sake, it is good to have some snacks and foods. Japanese people usually have sake with cuisine in home and Izakaya(Japanese types of pubs).
Jyunmai syu tend to have sweeter taste than others. Thus , it would be suitable with meat cuisine such as teriyaki source and gibier.
Of course, my comment is not all answer for you. You have your sense and there is perfect marriage with sake and cuisines.You can ask me any question if you wonder how to choose sake.