What is Daiginjyo? Ginjyo?
It are the polished ratio of rice which said Seimaibuai.
Daiginjyo: Seimaibuai less than 50% (removed more than 50%)
Ginjyo: Seimaibuai less than 60% (removed more than 40%)
Why polishing rice?
Outer of the rice contains protein and mineral. Protein is the source of amino acid and when it contain a lot the taste will come too much rich (heavy). And mineral harms the fermentation.
Generally, Seimaibuai will not come less that 35%.
If you want to now more about SAKE here below which I referenced
Here picked up some major Daiginjyo and Ginjyo which you can buy no Rakuten Global. So, enjoy!
Note: Some countries are restricted to import alcoholic beverage. Check before ordering SAKE.
Following store "Chuoshuhan" shows some countries condition. (4th paragraph from the bottom)