Design Summit/Mitaka/Travel Tips
If you're used to picking up a cheap local sim card when you travel, Japan might be a new experience.
As a non-resident, you're basically not allowed to have a voice service. Data-only sim cards are available, but expect to pay USD30-40.
http://prepaid-data-sim-card.wikia.com/wiki/Japan has all the details you'll ever need.
The simplest way TF has found is the "Japan Travel SIM (by Iijmio)". 1GB, 30 days validity, about 4000 JPY. https://t.iijmio.jp/en/index.html . You can purchase this from the Tokyo Tourist Information centre where they also speak English and Chinese and can give helpful travel advice for your stay in Japan. Just take the JR Yamanote line from Shinagawa Station near the venue to Tokyo Station ( http://www.tictokyo.jp/en/03_access/index.html).