Loose point of whisky regulation in Japan
There are no Japanese whisky PDO(Protected designation of origin) regulation and there are only domestic liquor tax law which define what whisky is in Japan.
It is actually much looser than other major world whisky regulation (Scotch, Bourbon/American, Irish and Canadian) especially about next 5 points
1) Process location
Japanese alcohol tax law requires only bottling in Japan to label as "Made in Japan" and "Product of Japan". SO it allows import bulk Japanese whisky.
All other world whiskies (Scotch, Irish, Bourbon and Canadian) must start local production process from mashing at least. But almost all whiskies uses malt made in UK or Germany today.
Japanese alcohol tax law doesn't have any aging requirement for whisky. It allows colored whisky by caramel without any aging in cask. Most of other world whiskies have regulation about minimum years and aging container's size and material.
3) Neutral spirits
Japanese alcohol tax law allows adding neutral spirits in whisky. It allows neutral spirits till 90% of total alcohol in whisky.
Scotch, Irish whisky, Canadian whisky and American straight whisky forbid neutral spirits.
Except for Japanese whisky, only low class American whisky (Blended whisky and Spirits whisky) allows neutral spirits in whisky.
4) Flavor additive
Japanese alcohol tax law allows flavor additive in whisky. It allows not only liquor but also non-liquor flavoring additive. If liquor, it should be Max 5% of total alcohol in whisky.
Scotch, Irish whisky and American straight whisky forbid it. Canadian blended whisky allows max 9.09% flavoring liquor but it should be more than 2 years aged liquor only for flavoring purpose.
Only Japanese whisky and low class American whisky (Blended whisky and Spirits whisky) allow non-liquor flavoring additive in whisky.
5) No export goods restriction
Japanese alcohol tax law covers only product sold in Japan and doesn't control export goods. So distillery who doesn't have whisky license are producing whisky for export although they can't sell whisky in Japan.
In add, if shochu (traditional Japanese sprirts) gets too much color by long cask aging, it can be labeled as just "liquor". Even labeling as "whisky" is not allowed in Japan because fermentation should be done by malt enzyme instead of Koji enzyme. But it is categorized as "Whisky" in US. Therefor some Shochu distilleries are exporting long years cask aged Shochu to US as rice whisky
Japanese whisky? type
Not sure if following whisky should be called "Japanese Whiskey"
Japanese whisky made from imported bulk whisky
Some Japanese whisky are made from mport bulk whisky.
Not only blenders but also some distilleries are producing Japanese whisky from imported bulk whisky. Especially almost all grain whisky for blended whisky are imported because there are no craft whisky distillery which has column still for grain whisky distillation.
Malt/blended whisky with neutral spirits
Adding neutral spirits in whisky is allowed only for Japanese and America although it's forbidden for Scotch and Irish.
Japanese alcohol tax law allows neutral spirits till max 90% of alcohol in bottle. In fact, it is cheapest category whisky and you can buy 4L size bottle in supermarket in Japan.
Almost all these whisky made from import bulk whisky. Most of them are blended whisky although there are a few malt whisky with neutral spirits.
Stainless pot still whisky
(Rice and other grain)
Japanese Shochu/Awamori (traditional spirits) distilleries are making whisky by stainless pot still which they are using for Shochu/Awamori.
It was quite common method in Japanse whisky blooming periods (1940s-1980s) but it can't remove sulfur components in malt which makes discomfort burn rubber smell in whisky. There a few distillery which is making malt whisky by stainless pot still today.
On the other hands, more other Shochu/Awamori (traditional spirits) distilleries are producing Rice whisky by stainless pot and exporting to USA.
Ghost distillery Japanese whisky
Some whisky distilleries described on Japanese whisky bottle label never disclose their address. These distilleries are suspected to not exist and their whisky is suspected to be just blended of imported bulk whisky by someone in Japan.
Some other whisky distilleries never mention to their own distillation still. These distilleries are suspected of not having distillation still and their whisky is suspected to be just blended of import bulk whisky.
Conceptor Japanese whisky
Some Japanese whisky in abroad never mention to producer's name. Concept is designed by trader and actual production seems to be outsourced to Japanese producer who is making "Japanese whisky" from imported bulk whisky.
Japanese whisky? producer
There are some Japanese companies exporting whisky from Japan although there are some dought whether thier product should be called as Japanese whisky.
1. JAPANESE WHISKY GHOST DISTILLERY
Some Japanese whisky producers claiming that they are distilleries are suspected of being a real distillery. Because some companies never disclose their distillation facility and the others never disclose even distillery address.
Kurayoshi distillery installed pot still in 2018 and distillery and pot stills were disclosed however Matsui Shuzo was supplying Japanese whisky from 2015.
2. JAPANESE WHISKY BLENDER
Currently there are only liquor tax law to define what whisky is in Japan and it requires only bottling in Japan to say Japanese whisky so that there are many "Japanese whisky" by bottling import bulk whisky. So there are some companies producing whisky without any distillation facility.
In add, it allows adding neutral spirit on whisky altough other countries don't allow it except for US.
There are 3 types producer in blenders, 1)Whisky without neutral spirit, 2)OEM whisky and 3) Whisky with neutral spirit in large plastic bottle.
3. WHISKY BY RICE/BARLEY SHOCHU DISTILLERIES
Shochu is traditional Japanese spirit made from rice, barley or other grains mainly in Kyushu, south Japan. Some Shochu distilleries are exporting cask aged Shochu distilled by stainless pot still as rice whisky to US.
In fact, Shochu has color less requirement by Japan liquor tax law so if it gets too much brown color by long years cask aging, distillery can label as just spirits instead of Shochu. However they can label as whisky in US because US law doesn't limit mashing enzyme from malt and one from Koji is also allowed for whisky.
Ohishi and Fukano are pioneer of rice whisky and they made rice whisky widely recognized new whisky category in US. Both are located in Kuma area, Kumamoto which is most famous rice Shochu production area.
4. WHISKY BY AWAMORI DISTILLERIES
Awamori is regional traditional spirits made from rice in Okinawa islands. Some Awamori distilleries are exporting cask aged Awamori to US as rice whisky.
In fact, Awamori has color less requirement by Japan liquor tax law so if it gets too much brown color by long years cask aging, distillery can label as just liquor instead of Awamori. However they can label as whisky in USA because US law doesn't limit mqshing enzyme to malt and Koji is also allowed for whisky.
They are using stainless pot still.
5. STAINLESS POT STILL MALT WHISKY DISTILLERIES
Normally whisky is distilled by copper still which can remove sulfur compounds in mash steam during distillation because sulfur compounds cause uncomfortable flavor like burn rubber.
Distillery normally add strong wood flavor on these whisky by new cask long years aging to vanish sulfur smell. However some distilleries are using vacuum distillation which refrains stimulating flavor.
Gyokusendo seems to use vacuum distillation
There are some "Japanese whisky" conceptors in the world today.
Normally these company make only concept and trade mark control. Only Aiko Import, BBC Spirit and Yoshino Spirits are real trader and others seems to be more offshore purpose companies.
Almost all thier whisky are rice whisky or bottled import bulk whisky.