This new kind of sparkling junmai daiginjo meets the Japan Awasake Association's certification standards, and takes twice as much time and effort to make as typical sake. Primary fermentation is done slowly in wooden tanks, at low temperatures, with another slow secondary fermentation period in the bottle. The bottles are inverted, then, to bring the dregs to the mouth, so they can be frozen and removed. The sake goes through low temperature pasteurization, and then allowed to mature for several months. The result is an unclouded sake with fine carbonation, a subtle sweetness, and incredible balance that surpasses traditional sake for something completely new. Doux Nature is a term used in champagne making, meaning a drink that is naturally sweet, without added sugar.