Update November 2014: Softbank has changed their WEP keys. This will no longer work. Sorry folks.
I finally figured out how to get wifi access using a laptop on the Shinkansen (Nozomi N700 only I think) or any Softbank “mobilepoint” access point. iPhone and iPad users will already have free “Softbank Wifi” access – this is normally locked to only an iPhone or iPad. Softbank only check your user agent.
Select the access point “mobilepoint”
Enter the WEP key: 696177616b
On Lion, a wifi access window will appear showing the mobilepoint login screen. Close this if it appears.
On the Develop menu (this might have to be turned on in Preferences) select the correct user agent:
For iPad Wifi (which gets you “2 years free wifi”) or iPad Wifi/3G users, select “Safari iOS 4.3.3 – iPad”
For iPhone users, select “Safari iOS 4.3.3 – iPhone”
Try and access a page in Safari and it should redirect you to the mobilepoint login page.
Enter your Softbank username and password. For iPhone or iPad 3G users, this is the “[email protected]” email address and password for the IMAP account you never use. For iPad Wifi users, use the “[email protected]” account with the password written on the letter you got bundled with your wifi-only iPad.
Since their portal now thinks you are actually logging in on the correct device, you have access. You can now stop using Safari and use Chrome/Firefox/Mail.app/whatever.
Alternatively you could fire up Skype and pay money per minute for Boingo wireless over Skype Wifi access after entering the mobilepoint WEP key. No thanks.