These are usually called Japanese Tourist Sheets by Japan collectors. Yours might actually be in the form of a booklet, if I'm looking at the scans correctly. They are not super-common but not scarce either. A lot of forgeries, even of common material, were propagated this way, although most sheets are usually a mix of legitimate postage stamps, revenue stamps, and forgeries. Definitely leave it intact, in my opinion, just for its historical value.
Here is an article from some years ago by Michael Rogers:
http://www.michaelrogersinc.com/Mic...ticle-1.htmlAnd here is a link to a monograph on the subject published the the specialist Japan organization, the International Society for Japanese Philately:
http://www.isjp.org/monographs/textmono17.htmlHope that's helpful!
-- Dave