This is a really fascinating subject covering these wonderful little works of art that originated in Japan in the 17th Century.
The Japanese Kosode and Kimono garments had no pockets so the men that wore these garments needed somewhere to put their personal belongings.  And so the Inro was invented to carry these belongings.  The Inro is a small box that was then held shut by a sliding bead, the Ojima and the whole thing was fastened to the securing cord using a carved button like toggle, which is the Netsuke.
There is now no longer an absolute necessity to wear Kosode or Kimono garments in Japan, other than perhaps for ceremonial occasions, but the Netsuke was adopted as a beautiful work of art by Westerners once the trade routes to Japan opened up.
In the late 19th and early 20th Centuries, Netsuke began to be made for export specifically to the Western market and are still being produced today by highly skilled craftsment in Japan.
There are many legends, and much symbology, in the creatures that are used for the Netsuke ornaments:


"Kaeru" is the Japanese word for frog and this also means to return.  Frog accessories are often carried by Japanese travellers to ensure a safe return from their travels. Frogs are also popular good luck symbols in Japan with the hope that money and fortune will 'return' to them.
You can find a small selection of Japanese Netsuke for sale in our website shop here: JapaneseNetsuke and also in our Etsy shop here: Etsy Netsuke 
You can find more information about Netsuke on Wikipedia here: Wikipedia Netsuke Article and on The Met website here: Netsuke: From Fashion Fobs to Coveted Collectibles