Hey Massaki,
Let’s troubleshoot the situation – please enable the debug mode (please see e.g. this article, first section entitles “Debugging With WP_DEBUG”, for instructions), refresh the website, and let me know if any error messages appear on the website itself and/or in the admin area.
Alternatively, you can provide access to your website’s WP admin and your ftp account, and I will do everything myself.
Sincerely,
Andrii / Satori Studio