SIWA is a collaboration between washi paper maker ONAO and Fukasawa Naoto, the esteemed industrial designer.
ONAO is located near Mt. Fuji, in the agricultural town of Ichikawa Misato, in Yamanashi Prefecture, an area boasting a 1,000-year history of paper-making. The company has perfected the technique of making washi, enabling them to create a material that is both waterproof and hard to tear.

SIWA products are made from naoron, a special type of paper developed by ONAO consisting of a mixture of wood pulp and synthetic fibres. This new material was developed using the ancient Japanese paper production technique of washi-suki. There are two types naoron: soft naoron, a mixture of wood pulp and polyolefin, which is soft and flexible. The other type is Recycled PET Fibre Naoron (RPF Naoron), created by adding recycled polyester fibres from used plastic bottles and textile products into the paper pulp. Both types of Naoron have the distinctive texture of paper, yet do not tear easily and are highly water-resistant.