@SHIGEAKI TETSUKA ,
Thank you for reaching out to the Microsoft Q&A platform. Happy to answer your question.
I suspect the issue might be disabling of NIC. By enabling NIC, you might solve this issue. The below link has the troubleshooting different reasons for this problem and provided troubleshooting steps.
https://learn.microsoft.com/en-us/troubleshoot/azure/virtual-machines/troubleshoot-rdp-connection
Please try these steps and let us know if the problem still exists.