Milan 2014: Japanese architect Jo Nagasaka has created a collection of spongy seats inspired by erotic bondage techniques by tying up blocks of foam and dipping them in rubber.

Nagasaka, who is principal of architecture studio Schemata Architects, based the Shibari series on the traditional Japanese art form of the same name, which means "to tie something with string".

The series, created for Japanese design brand Ichiro Inc, was presented at Spazio Rossana Orlandi during the Salone del Mobile in Milan earlier this month.

To create the pieces of furniture, foam sheets were folded and tied up into bulging forms with rope. They were then dipped in a rubber coating. Each piece is a different irregular shape and comes in black or white.

Different types of furniture - stools, sofas or tables - can be created by varying the way the foam is folded and tied. The lightweight items can then be carried around by using the knot as a handle. "We are envisioning furniture that generates different activities according to what we tie and how we tie," said Nagasaka.

Shibari is reputed to have evolved from Hojo-jutsu, the martial art of restraining captives by tying them up with rope. Samurai warriors honoured high-status captives by binding them in elaborate and flattering ways.

This later evolved into Shibari, an erotic form of bondage that involves tying up the human body in such a way that the knots and ropes act upon pressure points to create an effect similar to shiatsu or acupuncture.

See all our stories from Milan 2014.

Photography is by Hirotaka Hashimoto.