I need to get a sizeable amount of butcher paper, but I'm not having luck finding it on base. At least the people at the NEX depot couldn't help. 
I need to to cover some tables (like they do at Italian restaurants, which is the theme of the party), so I need several meters of it.  Any ideas where I might be able to purchase this off base?

Never gone looking for that, but the first place I would check is the Craft Store off of Blue Street, the name of the place escapes me again. A couple of stores on your right side after you exit the far end of Mikasa Plaza. The other place I would try is the first floor of HOMES.

Just guessing here... others may know better.

You could ask at the commissary if they can sell you a roll, otherwise maybe Costco.

Depending on how soon you need it, I would think your cheapest bet would be amazon.

I would check AVE down the 16. They have a sizable collection in the back of the store near the clothes of papers and foils used for cooking

All of the DoDDS schools have it in several colors getting it may be tricky.

Might want to check out COSTCO. http://www.costco.co.jp/eng/whs_860.htm

The ones in the States sell commercial size white butcher paper, and it isn't particularly expensive for a huge roll. You can probably get rid of the remainder at some place that has a bunch of kids with crayons or a school that wants to make banners. Or you could haul it around for the rest of your life and hone an obscure hobby of wrapping meats.

you can use the brown paper they sell at the NEX to cover boxes for shipping. Also wrapping paper works well, we have used it to cover tables for a few parties. you can use the back side if you want plain white.