Forbes Japan has and article by Chiho Kashiwagi (self-styled "rice hentai") looking into why the rice variety Kame-no-o is attracting attention.
Kashiwagi starts off by saying that Kame-no-o needs no introduction to sake fans, as it's a sake-specific rice (酒造好適米, shuzōkōtekimai) widely used in brewing. She then goes on to say that it's a normal table rice (飯用一般米, hanyōippanmai) like Koshihikari or Hitomebore. [I thought they were mutually exclusive...]
Kame-no-o (亀の尾, tail of the turtle) doesn't just make good sake, she claims, it's also great as a white table rice, in rice dishes like risotto or paella, or used for sushi. The variety was developed in 1893 in Yamagata Prefecture by the progressive farmer Kameji Abe [whose first name includes the character for turtle]. It's a parent strain of many modern popular table rice varieties, such as Koshihikari, Hitomebore, Akita Komachi and Tsuyahime. Kame-no-o itself was widely grown during the Taisho period, but was not suitable for modern agriculture with its agricultural chemicals and fertilisers and gradually fell out of production
That is, until it was picked up again in 1980 by the Kusumi brewery in Nagaoka, Niigata Prefecture. They sought out some seed rice and revived the variety, turning it into the sake Kame-no-O (亀の翁, old man turtle). [Ah, the puns.] It featured in the manga Natsuko no Sake, leading to more breweries turning to Kame-no-o for their rice supply.
Some breweries have been growing Kame-no-o in a more traditional style with no agricultural chemicals or fertiliser for about a decade. One is Niida Honke in Koriyama, Fukushima Prefecture - founded in 1711, they grow Kame-no-o for their organic shizenshu (自然酒, natural sake). 18th generation owner Yasuhiko Niida says they started using Kame-no-o as it's indigenous to Japan and also because of the most popular rice varieties in Fukushima - Fuku-no-hana, Kyo-no-hana and Kame-no-o - it's the least used of the three.
Just goes to show that everything goes around in cycles - Kame-no-o may not have worked well with modern fertiliser-assisted agriculture, but comes back into its own with organic farming.