The new sign-in method requires your Yahoo! JAPAN ID that is linked to your Yahoo! JAPAN Business ID (Business ID).
Sign-in using the registered password is no longer available.
Link your IDs from the "Yahoo! JAPAN ID linkage" page.
To link your IDs, you need to know the registered email address and phone number.
If you aren't sure, ask the administrator (a user who has administrator permission or tool access permission).