This little shop in Ueno’s Ameyoko-cho market district sells rubber celebrity masks. They only cost 2,000 yen or so and would certainly make a unique souvenir of Japan. It’s call the Ueno-ya, and the masks page is here.

Hatoyama Yukio Antonio Inoki
Kinnikuman Kuidaore Clown
Eyeball Ozawa Ichiro
Asashoryu Buddha
Anime character (This one costs
13,000 yen)		 Godzilla

To get there, go out the North Exit of Okachimachi Station and turn left, walking along the JR tracks. Turn right at the second corner and you’ll see it immediately on the right.
The address is 6-3-9 Ueno, Taito-ku, Tokyo (Japanese: 東京都台東区上野 6-3-9). Tel. 03-3831-0631
The masks can also be bought online.