Koizumi Seisakusho, which was founded in 1889 and has been in business for nearly 135 years, mainly produces copperware. Inheriting the regional traditional craftsmanship of Takaoka City, Toyama Prefecture, the factory initially focused on the production of Buddhist utensils, and later began the production of copper alloy castings such as copper musical instruments, mechanical parts, and precision parts.

In recent years, Koizumi Seisakusho has been obsessed with studying copper musical instruments, and has boldly tried various methods to produce the best sound quality of metal, thus producing a variety of popular music products.

Koizumi Seisakusho has been given many opportunities to restore Japanese cultural heritage, including restoring the clock at the "Eromon Gate" designed by architect Gaudi in Fukuoka in 2007, and restoring the "Hibiya Park Free Gate" in Tokyo in 2010. bell".