1. After logging in to the control panel, click on the target site from [WebHosting Plesk].

2. You can connect to Plesk by clicking "OPEN" in "MORE TOOLS".

3. Click "SSL/TLS証明書 (SSL/TLS Certificate)" from Plesk management screen.

4. Choose the target certificate in "Choose File" and upload it from the "Upload Certificate" button.

5. Return to the Plesk management screen and select "ホスティング設定(Hosting Settings)".

6. In "ホスティング設定 (Hosting Settings) > "セキュリティ(Security)" >  "証明書(Certificates)", choose the uploaded certificate and click "適用する(Apply)" at the bottom of the page.