It's a Japanese Arisaka with the Mum somewhat intact except for the crossed chisel marks (was to deface the mark of the Japanese Imperial family). Many of these Mums were ground clear off. As Miller Tyme said it was probably a vet bring back. I have one just like it. Can you show us a pic of the front sight ? Does it have the flip out wings on it ? Also is the butt plate metal or wood ?
Helpful links... and they are a blast to shoot...
Markings on Japanese Arisaka Rifles and Bayonets of World War II
BANZAI
They're only a blast to shoot if you can find ammo!
Think plane jane handgun ammo is scarce? Try to find 7.7 Japanese!
-J-