Multi Site Multi Domain
I believe you need to use tweak the config/general.php file in order to have a baseUrl for a site that is a different domain name.
'siteUrl' =&gt; [
    'english' =&gt; 'https://www.mysite.com/',
    'japanese' =&gt; 'https://www. myjapanesesite.com/',
],

See documentation at: https://docs.craftcms.com/api/v3/craft-config-generalconfig.html#siteurl