Well if this isn't a hidden gem...
Classic koshu notes of honey, beeswax, lanolin, sweet potato, mushroom, soy sauce, white miso, roasted chestnut, white raisin, smoked meats, and sesame, with a unique spin from the sake's uncharacteristically high acidity...a squeeze of fresh lemon. Very lightly sweet, but not at all a dessert sake. Just enough sweetness to balance the high acidity. Definitely appropriate for savory cuisine.
Hidden how? Well I've never come across this before, and it turns out it's the last batch of inventory on a limited release. Hot on the koshu hunt, I found a product writeup on the Umamimart blog and immediately cross checked it with my distributor's inventory. I generally trust Ichinokura's products, and the backstory on this one made me curious, plus there was a little bit available at a really good price.
Unusually for sake, the design intent was to pair with a Miyagi regional specialty: beef tongue. When they originally brewed the sake it was far too acidic to be enjoyable, so the toji decided to age it rather than wasting the batch. After 3 years aging at ambient temperature the flavor had mellowed and integrated around the high acidity, so they bottled it for sale as a limited release. Thanks to the fact that koshu is a relative unknown, it has been aging in small format bottle-- about 2 additional years-- at the distributor's warehouse.
My thought was: even if this has been sitting around the warehouse for years, the way it's made, I bet it will continue to improve in bottle (low polish, high acidity)...So I figured what the heck? Might as well pick it up.
When I tried it I felt like a crazy person, sending out emails like "how much is left??" because it's by far the best value I've encountered for an authentic koshu, and even better, one with this beautiful high acidity. It's not going to last long, and it's an incredibly affordable first step into koshu. So if you're curious about koshu at all, this is the one to try.
85% Polish Toyonishiki from Miyagi prefecture, aged for 3 years at ambient temperatures, plus an additional 2 years in bottle. There is very little information available on how this is made otherwise, such as fermentation method, koji or yeast, so I'll just have to leave that to your imagination. However, I would wager a higher than usual level of koji for added umami and perhaps a natural fermentation method like yamahai or kimoto in order to achieve the high acidity.