Be sure to check how many items are in a package. Many food items are individually wrapped, particular souvenir ones, and while that's great for handing around, the packages are deceptively large for the quantity. I've gotten a good sized box before only to discover to my horror later that it only contained 8 or 10 individually wrapped carefully packed cookies inside.

Whatever you get, whether weird flavors such as wasabi Kit Kats, or cartoon characters packaging, or just plain rice crackers, as long as there's Japanese writing on it will be undoubtedly be appreciated and a topic of conversation when passing them out back home.