Based in Gifu Prefecture, Miyama Riken provides plating for metal and plastic components used in applications including plumbing fixtures, residential equipment and automotive parts. The company has particular expertise in black and colored decorative plating.

Seiwa said the acquisition will expand the range of substrates and surface-treatment technologies available across its group. Its existing finishing operations include electrogalvanizing, electrocoating, chemical conversion treatments, metal painting and other specialized processes.

Miyama Riken reported fiscal 2026 revenue of approximately ¥1.72 billion and operating profit of ¥189 million. The company employs approximately 83 people. Financial terms of the acquisition were not disclosed.

Seiwa also expects the companies to share sales networks, purchasing and distribution resources and manufacturing-management practices. The group highlighted Miyama Riken’s use of digital production and quality-control systems, including electronic work instructions, QR-code tracking and automated collection of inspection data.

The acquisition remains subject to completion of the planned share transfer.

The transaction expands Seiwa’s finishing capabilities across both metal and plastic substrates and adds specialized decorative plating technology. It also highlights continued investment in automated quality control and digital manufacturing within industrial surface-treatment operations.