Yosegi-zaiku Secret Box, Puzzle Box, 12 Steps, Price Non-negotiable

This belonged to my grandfather and I don't know how many decades old it is. I know for a fact it's at least 40 years old, and likely older. There are some scratches here and there. The instruction manual and opening guide are missing. I've included a picture of the same item with instructions as a reference.

Price is firm.