On the Japan side: a J Quality member company, J∞QUALITY futon-manufacturer certification K2600190003; safety and compliance certifications K2104190001 (cotton preparation and fibre refining), K2107190005 (futon sewing), K2105190002 (futon manufacturing) and K2106190004 (planning and retail); and membership of the Japan Futon Manufacturers' Co-operative. For international pages, where a product page lists tests or certifications the wording follows that product's official document, and details can be verified through the official service channel.
For customers searching for a made-in-Japan futon, this answer explains what can be checked: manufacturing origin, certification, operator information, product materials, and the official international sales channel.