About file sharing with accounts outside the tenant.

In Google Drive, you can share folders or files with accounts (email addresses) outside of your tenant.
When a folder is shared, it enters "Visitor Session" mode, and actions such as file uploads are not allowed.

Please use an email address other than @keio.jp.
Please make sure to keep the notification checkbox selected.

If there are no issues with the address you have set, click on "Share anyway" to proceed.

You will receive an email with the subject "Item shared with you: fileName."
Please click on "Open" or the URL provided in the email.

You will receive an email with the subject "Google Verification Code."

Enter the Google verification code and click "Next."

The shared folder or file will be displayed.
Once you complete the authentication process, the verification code will be valid for 7 days. During this period, if you share again with the same external email address, a verification code will not be required.