katana made with wood on the outside. name?

[n4rumi]

i recently bought a cheap katana which is made with woode on the outside but has a real blade on the inside, i was wondering what it was called and where i could find a good one. ive heard somewhere that this is a "hidden" katana or something of that sort. it looks like a curved piece of wood. please reply, thanx

[UrbanStyle]

As far as I know the name is Katana Shirasaya.

[lordtariel]

A Shirasaya was essentially a holder for a blade that was not going to be used for a while. They were not intended for actual combat.