Koikawa Shuzo, founded in 1725 and based in Yamagata Prefecture, draws on three centuries of local brewing knowledge while its current owner brings 11 years of experience as a wine sommelier to the craft. The brewery relies exclusively on Yamagata-grown rice and Yamagata-developed yeast, and led efforts to revive the heritage Kame No O rice variety. Koinokawa is Koikawa's junmai label, designed to express the rice's character across all temperatures with particular depth when warmed.