Go out to Shibuya 109 for an hour or two. I broswed through all the floors when I was there and found MILLIONS of things I couldn't find out here in Canada. Their fashion sense is very different. And quite fun too! :3

Also Purikuras and UFOs' can sometimes be exclusive to Japan. I know there aren't any like that out here~

Japanese clothes and shoes and bags and accessories
Strawberry kitkat, strawberry cheetos, strawberry oreos chocolate bars and a whole lot of candies and chocolates!!!
Poppin cookin'
Konapun
Japanese brand cosmetics

If it were me, I'd go for pocky, as around here they only have chocolate and strawberry. Also, I want to find those cool drinks with the marble that I keep hearing about. Snacks is first on MY list xD

And I want to get anime merch. I'm such a geek :mtongue:

when you get there...
 

Ask around if you can buy a list with things sold exclusivly in Japan. I apologize if it sounds mean but i'm sure that you can find at least one thing in every store you enter. Good luck

:D That's gold.

But seriously, I visited friends in London while living in Japan and took a bunch of stuff from the 100 yen shop that I had never seen in any other country. I wrapped each item in Japanese newspaper.
When I gave them their gifts they were fascinated by the newspaper. Some of them even made me promise to send a couple of pristine newspapers over to London once I got back to Japan. Ones that they couldn't buy in London, just so it was even more mysterious.