An inro, used for carrying small objects, is a tier or nest of small cases skillfully fitted into one another. It is suspended by a looped silk cord that passes through cord runners along its sides, then through a sliding bead (ojime), and then under the obi, where it is fastened to a netsuke that rests securely at the top of the sash. The ojime is moved up or down to allow the cases to be opened and closed. The inro was worn almost exclusively by men, whose narrow sash neatly accommodated the ensemble. Women carried small objects by placing them in their roomy sleeves or tucking them into their wide obi.

The literal translation of inro is seal basket, suggesting that originally it was used to carry personal seals. In their earliest manifestation, Inro, which took a long and arduous time to make and were therefore expensive, were worn only by the daimyo and samurai. By the second half of the Edo period, the economy was flourishing and merchants and townspeople were becoming more affluent; anymore who could afford an inro was allowed to wear it. Inro were most popular during the 1700s and 1800s, when they were primarily used to hold medicines. During this period, inro evolved from a purely functional object into a fashionable item, a form of jewelry for those denied personal adornment by the countrys strict sumptuary laws. Well-to-do merchants frequently had inro made to complement a high-quality kimono, for a special event, or simply to indicate their prosperity.

Historically, the inro is about four hundred years old, roughly corresponding to the Edo period. Its precise origin is uncertain, but evidence, especially that recently provided by documents in the Tokyo National Museum, indicates that the portable inro was definitely in use by 1600. The first inro for personal wear specifically mentioned in the literature was owned by Toyotomi Hideyoshi(1536-1598), who gave it as a gift to a temple abbot around 1595. This inro subsequently passed through many hands.

Inro were made of wood,woven reed, pottery and lacquer. The evolution of the inro resulted in what has been called the finest miniature lacquer art ever known, a utilitarian object of exquisite beauty that was highly prized during the Edo period.