Tokyo Subway Map T Shirt

Hi

I'm looking for a tee shirt with a subway map on it. I bought my son many years ago a tee shirt like this with the Osaka subway map on it. He is still wearing although it has a couple of holes in it. Lol. I'd like to buy him another but with a Tokyo subway map. Actually, any Japan subway map will be good.
Does anyone know where I can purchase one in Tokyo?
I'll be staying at the Keio Plaza hotel in Shinjuku but will be traveling to other areas in Tokyo.
Thanks for the help.
Lil

Try the "Engrish.com" online store... yes you read it right, it's "Engrish..." :)

Some great options here!

http://www.redbubble.com/people/saburokiyoshi/works/5171813-tokyo-subw...
http://www.redbubble.com/people/hunnydoll/works/10396423-tokyo-metro-s...
http://www.redbubble.com/people/robobop/works/5245060-osaka-subway

Tokyo Metro does not seem to sell the route map T-shirt.
Route map T-shirt of the license agreement are Internet sales.
Lists that are sold in the Tokyo Metro
http://www.metocan.com/shop/contents?contents_id=162611
Goods are selling well in underground museum of Kasai.
Perhaps, it may not only children's T-shirt.
http://www.chikahaku.jp/goods/index.html

Thanks, AK and By.
I'd really like to take one home with me. Does anyone
know where they might be in Tokyo? Would
I be able to find one in Asakusa at the temples?
Thanks again.

There are no official Tokyo metro T-shirts.
Osaka municipal subway T-shirt was only sold for 1000 shirts for celebrating it's 80 years anniversary.

However, Chikatetu-hakubutsukan(Metro Museum), Kasai station has it's original T-shirts for 1,200 YEN per shirt.
http://www.chikahaku.jp/goods/images/t-shirt_b.jpg
This shirt is not Tokyo metro official shirt, it's Metro museum official shirt.

Unofficial shirts are available at Rakuten store. There is no physical shops available so you need to order via internet and deliver to where you stay.
http://item.rakuten.co.jp/chiiroma/s2358/?scid=af_ich_link_txt

The shop is available Nankai, Hankyu and Kyoto unofficial railway map oh T-shirts.
http://item.rakuten.co.jp/chiiroma/c/0000000110/

Thanks Tokyo friend.
It looks like I have to order online.