I entered the Two-Factor Authentication (2FA) code, but I still cannot log in. What should I do?

If you have received the authentication email but the process fails, the most common cause is the 'Expiration of the Verification Code.' Please follow the troubleshooting flow below to resolve the issue.

Troubleshooting Flow for Authentication Issues

1. Request a New Session

   Verification codes are security-sensitive and remain valid for only a few minutes. If too much time has passed since the email was sent, the code will expire. Please return to the login screen, restart the 'Log In' process, and enter the newly issued code immediately.




2. Pre-Entry Checklist

   Single-Byte Characters: Ensure you are entering digits in half-width (alphanumeric) format.
   Check for the Latest Email: If you requested a code multiple times in a short period, ensure you are entering the code from the most recent email. Older codes are automatically invalidated once a new one is requested.




3. Handling Delays or Missing Emails

   If the email does not arrive within a few minutes, please check your Spam/Junk folder or ensure that your mail server is configured to permit emails from our domain (e.g., @kosei.com).

Still Having Trouble?

If the steps above do not resolve the issue, your account may be temporarily locked for security reasons, or there may be a system synchronization error. Please contact us via the Inquiry Form with your full name and registered email address, and our technical team will assist you.