The founder of the brewery first traveled to Asahikawa, Hokkaido by Kitamaebune (traditional trading ships) and began brewing sake there. In the late Meiji era, he returned to Toyama and started making sake under the name Iwaizumi. Later, a new brand called Masuizumi was created—an auspicious name combining the family name Masuda with the meaning “a spring full of good fortune.” This brand has since become their flagship label. The fourth-generation brewer, Mr. Keijiro Masuda, studied fermentation science and teamed up with Koichi Sanpai, who would later be known as one of the “Four Great Noto Toji” (master brewers). Together, they crafted highly refined ginjo sake, known for its precision and quality—often compared to fine machinery. Their sake has frequently won gold medals at national tasting competitions and helped raise the reputation of Toyama's sake industry. They also continue to explore new directions in sake brewing, using wine yeast and aging in barrels, pushing beyond traditional boundaries to create sake with unique and modern appeal.