No Added Gas, No Added Sugar: An 8% Toasting Sake from Ibaraki

On 22 August 2026, Isokura Shuzo, a sake brewery in Kasama, Ibaraki Prefecture, north-east of Tokyo, released a sparkling sake called “Jun Ibaraki-san Shizen Happo Junmai Daiginjo”. The aim was a sake worthy of the kanpai, the toast that opens a meal. No carbon dioxide is added afterwards and no sugar is added; the bubbles come solely from the gas produced by the sake’s own fermentation. The alcohol content is 8%.

Designing the Bubbles Backwards from the Amount of Koji

Many sparkling drinks are made by adding gas. Another common method is to add sugar during fermentation to help the bubbles form. Isokura Shuzo used neither. The sugar produced by koji (the mould that converts rice starch into sugar) becomes the source of the bubbles directly. The brewery therefore worked backwards to decide the amount of koji needed to achieve the desired strength of fizz, and then brewed it using the same process as ordinary sake, explains president Takahiro Iso.

After bottling, the gas pressure continues to be measured, and once it reaches the target, the sake is heat-pasteurised to halt fermentation. The finished gas pressure is slightly lower than that of typical champagne. The rice used is Hitachi Nishiki, an Ibaraki sake rice grown by farmers in Kasama. The grade “junmai daiginjo” refers to the top category, made without added brewing alcohol and with the rice polished down to half its size or less. Ordinary sake is 15–16% alcohol, so 8% is roughly half of that.

A Bottle Born from a Study Group of Chefs and Retailers

The project grew out of the “Society for Nurturing the Finest Ibaraki Local Sake” (Saiko no Ibaraki Jizake o Sodateru Kai), founded in 2024. About 30 people take part, including owners of restaurants and sake shops in the prefecture, as well as sommeliers. The chairman is Satoru Iijima of the French restaurant Restaurant Iijima in Mito, and President Iso serves as secretary. The dishes envisaged were Ibaraki’s premium beef brand Hitachi beef, tempura, eel and French cuisine, among others. The flavour was refined as an opening drink to be served before dishes made with Ibaraki ingredients.

The price is 5,500 yen for 720 ml, or 6,600 yen in a wooden box. Shipments in 2026 are limited to 600 bottles, which will be sold only through restaurants and sake shops within Ibaraki Prefecture.

How to Enjoy It in Europe

There is currently no prospect of this brand reaching Europe. Even so, it offers a hint on how to choose a sparkling sake. Check the label or the importer’s description to see whether gas has been added or whether the bubbles come from fermentation in the bottle. A lower alcohol content is another clue. Serve it well chilled in a flute or a white wine glass, and it works as an aperitif in place of sparkling wine. Paired with fried food, oily fish or beef, the bubbles and gentle acidity refresh the palate.