If you have forgotten your "MyJALCARD Authentication Code," please go through MyJALCARD again to register for a new "MyJALCARD Authentication Code." After logging in to MyJALCARD, click on "New Registration/Forgotten Registration" on the top left of the screen and complete the procedure.
[PC site]
[Smartphone site]
Once you complete the new registration procedure, the previously registered "MyJALCARD authentication code" will become invalid.