This is a sheath; Japanese sword case.
It was manufactured in Edo era ; 1603-1868
Sword is originally arms.
But Edo era was peace , especially after middle of Edo era, there were no big civil wars.
Thus sword became a symbol of samurai, not to use as arms.
Long sword was rarely used in Edo era, but small knife was usually used as like a cutter knife.
I imagine that samurais enjoyed using a small knife and sheath like we enjoy using fountain pen.
Sheath and brim also became art in Edo era.
Samurais loved its beauty.
And they changed these items season by season.
This sheath is expressed Uryu; rain dragon.
Uryu ( rain dragon ) means young dragon.
Uryu also means a special carp which rising up waterfall.
Our legend says that the carp lived long became a Uryu.
Our ancestors though young dragon is same as a water God.
In addition, they liked young dragon as a symbol of growth.
Young dragon was designed as a family crest and temple crest.
Round eyes of the dragon are expressed as water splashes by inlaying gold.
Elegant waving body line was expressed by Suemon ( a kind of inlay ) and installed on engraved sheath.
This engraving in called Nanako.
Nanako means eggs of fish. Nanako pattern is similar to pique weaving.
The craftsman name was not engraved, but he seemed an excellent skilled craftsman.