You can configure your access to My SoftBank from a PC, iPhone, or SoftBank X Series so that it will request you to enter your PIN number when you login.
This setting does not apply to the SoftBank 3G and Prepaid mobile phone versions of the service.

1.Access and login to My SoftBank and then click
"Require PIN number entry at login".

2.After logging in, check "Require PIN number entry at login".

3.Check the settings you have entered, and then click "Apply the above settings".

4.This completes the PIN number entry setting.
You will be prompted to enter your PIN number the next time you login.