Thank you for letting me know this rule. I should have been aware of it.
Yes, I'd love to share with you some pieces.
Thank you for the question. I agree with you. Unless you have a local friend it may be difficult to find stamp shops in Japan.
Here is a list of stamp shops in Tokyo, published by the Japan Stamp Dealers Association.http://www.jsda-tokyo.jp/member01-tokyo.htm
I've actually started my journey to find good stamp shops today.
In the meantime it may be worth to visit the Philatelic Museum.
Direction: 1 Chome-4-23 Mejiro, Toshima-ku, Tokyo-to 171-0031http://www.yushu.or.jp/museum/