If mixi.jp is online but you are having trouble getting the website to load, To resolve the problem, try one of the solutions below:
Browser Related Problems
Force your browser (Chrome, Firefox, Explorer, etc.) to refresh the webpage by pressing CTRL + F5 keys at the same time.
Clear cookies from mixi.jp and your web browser's cache to make sure that you have the latest version of the web page.
If you have recently installed a browser plug-in or firewall software that might be causing trouble. Try either disabling it temporarily or un-installing it.
Open a new tab and check if you can reach another website like google.com.
Fix your DNS Problems
The Domain Name System (DNS) is a server that translates the website's domain name into the IP address so your browser can connect to mixi.jp. Typically your Internet service provider (ISP) runs DNS for you. The inability to open mixi.jp by domain name usually indicates a DNS problem.
Try accessing the mixi.jp via its IP address directly. If you can access the mixi.jp using its IP address but not its domain name, chances are that you have a DNS problem.
Turn off your router and wait a few seconds, then turn it back on again.
The problem might be your DNS cache outdated or corrupted, You have to flush it out. For Windows:
open command prompt and type "ipconfig /flushdns".
If you can access mixi.jp from an alternative network like your mobile internet connection or office Internet connection, But mixi.jp is not working on your computer, Try changing your DNS to a public DNS service like Google Public DNS or OpenDNS.