To always findthe next way forward


From a Leading
Jewelry Industry Firm

Kohsai factories are located
exclusively in Japan.
We harness our technological strength,
a fusion of craftsmanship and machining,
to maintain complete control over all
aspects of production: from quality,
to finishing, to flexibly responding to customer demand, and even to mass production.
We strive to improve the usability and reliability of our products as a technical jewelry company.

Production system(Factory)

Centralized production at our headquarters/factory.This system boosts our technical competence and supply flexibility

Our inhouse factory in Kai City of Yamanashi Prefecture serves as our centralized production hub.We are building a professional group of jewelry-makers, cultivating craftsmen and other talent, pursuing cutting-edge technologies, ensuring end-to-end quality, and honing our processes.We strive to grow as a leading jewelry processing company, under the banners of sustainability, technology, and globalism.

A technical jewelry company in constant pursuit of the most cutting-edge technology

No other company can boast our unique combination of craftsmanship and cutting-edge machining.We are of course committed to our quality and delivery promises, but are also diligent in further improving our technical competence.

Craftsmanship for not only people and society, but also the Earth

Our people-friendly products eliminate substances that may cause allergic reactions, like nickel, cobalt, cadmium, lead, and mercury.We are also committed to the environment in the interest of sustainable business.

Initiatives to improve not only productivity, but also literacy and awareness

We’ve implemented schemed to improve productivity through across-the-board reductions in waste from excess and overburden.We are also working to improve literacy and awareness through management and SDG-related training.