NIHONSHU SHIKA
21% alcohol is almost the limit for brewing sake. At this level, the yeast is killed by the alcohol it has created. Under the Sake Tax Law, the alcohol content of sake must be less than 22%.
However, Gorohachi is classified as a liqueur, not sake. According to my research, it was classified as sake before 2006. However, due to a revision of the Sake Tax Law, it can no longer be called sake. But rather than change the taste and make it sake, Kikusui chose to keep the taste even if the classification was changed.