there was a thread a while back about someone trying to return a flag like this to the family of the soldier. it had a link to an organization that helps facilitate this.

here is the thread: https://www.reddit.com/r/japan/comments/3dtw8r/looking_to_return_this_to_its_rightful_owners/

This is a personal flag signed by family and friends. Sort of a good luck totem. Very valuable. Get provenance if you can and do library research. Good luck.

I'm a cryptographer and so please delete this comment if it is out of scope. In cryptography, we have this thing called Ring Signatures (I'll spare you the details), and people have pointed out an interesting connection to the Edo-period Japanese method of signing a document without revealing the order of support. For example, John Hancock being the first signatory of the US Declaration of Independence has made his name synonymous with "signature" itself, but if farmers wanted to support a complaint against their ruler they probably don't want to be signer #1.

If you translate this source it explains that sometime in the mid-18th century, farmers established this type of "umbrella signature" or "karakasa renpan" where a document was signed in this circular fashion as a show of support as an equal among all signers. Unfortunately, I do not know if OP's flag has anything to do with this, and I only noticed brought this up because of the (possibly coincidental) pattern of signatures.

Thanks everyone! Very helpful information. I knew reddit would save the day on this one. I will be contacting OBON2015 and following the instructions on how to return the flag to the family of the soldier.

This may be significant. If so it needs to be returned.. Start here and keep us posted: http://obon2015.com/english/