Help identifying mask - where to buy?

Hello, I was wondering if anyone might be able to help me identify the circled monkey character used for a mask in this photo: http://threeghosts.net/stuff/Tokyotoys4.jpg

I am a very big fan of Naoki Urusawa the comic artist, especially 20th Century Boys. That mask was used in his comic, and I'd love to buy one the next time I'm in Japan.

Is there a name for this character so that I might be able to search for it? Would anyone happen to know where I might be able to find a mask like this in Japan - are they common?

Any help would be really appreciated. :)

Not a monkey but Ninja Hattori-kun (note the blue garment visible around his face).

http://en.wikipedia.org/wiki/Ninja_Hattori-kun

AK, thanks so much for the information! That helps a lot!

Is it common to find Hattori masks in many stores in Japan? I only came across one vendor that sold masks when I was there last year - in a stall at a street fair in Kyoto.

Alana,

A quick internet search tells us that the mask is hard to get now as it was used iconicly in the popular movie "20th Century Boys." Some people seem to seek luck in internet auctions.