Yamatanmasamune is produced by Yagi-Shuzobu, founded in 1831 in Imabari, Ehime Prefecture, where the founder adopted the house name Tamba-ya and named the sake after both his family crest and the legendary blade Masamune to express its sharpness. Over 90 percent of production uses Ehime-grown rice varieties including Matsuyama Mii and Shizuku-hime, with brewing water sourced from the Soja River, which rises in the Takanawa mountain range. The brewery maintains year-round cold fermentation through full-facility climate control, enabling brewing conditions equivalent to colder northern regions despite Ehime's mild climate.
