Tamagawa Shizenjikomi Yamahai Junmai Kamenoo Muroka Namagenshu

Tamagawa Shizenjikomi Yamahai Junmai Kamenoo Muroka Namagenshu (玉川 自然仕込 山廃純米酒 亀の尾 無濾過生原酒) is a limited-release junmai yamahai from Tamagawa's Shizenjikomi (自然仕込, "natural brewing") series made with Kame no O (亀の尾) rice grown in Fukui Prefecture . Although Kame no O is often associated with sake brewing, it originally developed as a food rice (飯米 hanmai) and later became an ancestor of well-known Japanese rice varieties such as Koshihikari (コシヒカリ), Sasanishiki (ササニシキ), and Tsuyahime (つや姫).

For this release, Kinoshita Shuzō utilised Kame no O for the first time, brewing the sake with an unusually low polishing ratio of 88%, which left much of the rice's outer layer intact. The sake was produced without added yeast as part of the brewery's Shizenjikomi series, which is characterised by higher acidity and amino acid levels. Koji production was extended to around 72 hours, compared with the more typical 45 hours.

The result differs noticeably from that of many sakes made with Kame no O or low-polished rice. Rather than emphasising roughness or heaviness, it combines a dense, full-bodied profile with a smooth texture and a relatively gentle mouthfeel. The aroma shows grain-like and lightly roasted notes, alongside subtle strawberry-like hints. Rich umami and acidity are balanced by a clean finish with faint astringency and lingering complexity associated with older rice varieties. The sake has a yellowish colour and develops gradually on the palate, making it suitable for pairing with food. It pairs well with grilled fish, simmered dishes, poultry, pork, mushrooms, and root vegetables. This is the tenth release in the 2025 brewing year of Tamagawa's Shizenjikomi series and one of the brewery's more experimental junmai yamahai bottlings.

Kinoshita Shuzō, in Kōyama, Kyōtango, Kyōto Prefecture, was founded in 1842 by the fifth head of the Kinoshita family, Kinoshita Zenbei (木下善兵衛), who reportedly used the harvest from almost thirty hectares of rice fields and the copious spring water gushing from the mountain behind the brewery. The hereditary name Zenbei was passed down to the 6th and 7th generations. Then, the company was led by the 8th, 9th, and 10th generations (Sentaro, Zenichiro, and Juichi, respectively) before being handed over to Kinoshita Yoshito, the current president and the 11th in line.

The brand name Tamagawa can be translated as "Jewel River." The name is thought to refer to the Kawakamidani River, which flows by the brewery. The character 玉 (tama) means "jewel" and carries sacred connotations in Japan's native Shinto . 川 (kawa or gawa in compound words) means river.

Kinoshita Shuzō is one of the few Japanese breweries with a foreign tōji, Philip Harper. Born in the UK, he graduated from Oxford University. He taught English under the JET programme until he discovered sake. He worked at Umenoyado Sake Brewery for ten years before taking and passing the Nanbu Tōji Association's qualification test in 2001, earning him the title of 'Tōji'. He was the first foreigner to become a tōji (and the only one at the time). He then worked at Umenoyado Shuzō, Daimon Shuzō and other breweries before becoming tōji at Kinoshita Shuzō in 2008.

Kinoshita Yoshito gave him full responsibility for everything except following the locally favoured taste of regular sake and daiginjō. He immediately began producing kimoto sake, which does not use lactic acid during brewing, and yamahai, which uses only natural yeast from the brewery. In addition to new sake types like 'Icebreaker' and 'Time Machine', Tamagawa's legacy is reflected in the sake he produces.

Along with the new master brewer, the brewery's logo was redesigned by Sakane Katsusuke with an innovative design to symbolise the new Tamagawa. It is now widely known as the 'Marutama mark' (丸玉マーク).