This is a catch-all category for shochus that fall outside the big four, and includes over 50 other ingredients approved for distilling shochu. Here’s Japan Distilled’s article on the matter and includes the list of accepted ingredients, they call this genre of shochu “Aromatic Shochu“

You’ll note that many of these items (Leeks?) could never support a fermentation/distillation mash like the main shochu ingredients, and so generally rice or barley is the backbone of the first mash, with the special ingredient added along with more rice/barley during the second/main fermentation. 

Soba/buckwheat is actually the largest segment of these sub-ingredients, and its most famous example is Unkai, the namesake shochu of Unkai Shuzo in Miyazaki, which we are huge fans of.  It’s similar to mugi shochu but with more nutty and vegetal notes; refreshing with water or ice.

But by far the most famous single aromatic shochu is Tantakatan, made from red shiso leaves by Godo Shusei in Hokkaido. However, it actually doesn’t qualify as honkaku shochu for undisclosed reasons, so it might be multiply distilled or made in non-pot still. It’s kind of an intro shochu, light and fragrant, and great with ice at just 20% ABV.

Many of the shochus in this category are somewhat gimmicky and ultra-regional, using the local produce of the area as the base ingredient for shochu. For me, apart from soba, the other “serious” aromatic shochu ingredient is black sesame, the most famous of which is Beniotome from Fukuoka. If you’re familiar with Asian black sesame desserts, Beniotome’s aroma is like roasted 黑芝麻糊. Of course there’s no sweetness on the palate, but in the mouth it’s still incredibly savory and rich.

Anyway, there is a ton of variety in the aromatic shochu category – I’ve tried random shochus with Pumpkin, Seaweed, Milk and Sour Plum (not umeshu, but sour plum shochu), and while none of them will ever replace the big 4 shochu ingredients for me, it’s a lot of fun. That’s part of the amusment of drinking shochu that there’s always a type you’ve never seen; a brand which you’ll never found outside its home province. You’ll never try them all, but it’s fun to try!