The Collaborative International Dictionary of English v.0.48:

Inro \In"ro\, n. [Jap. inr[=o]; in seal + r[=o] box.]
   A small closed receptacle or set of receptacles of hard
   material, as lacquered wood, iron, bronze, or ivory, used by
   the Japanese to hold medicines, perfumes, and the like, and
   carried in the girdle. It is usually secured by a silk cord
   by which the wearer may grasp it, which cord passes through
   an ornamental button or knob called a netsuke.
   [Webster 1913 Suppl.]