When you pass a string with Japanese characters to escapeshelllang() function in PHP, those characters are silently removed. Here is the solution cited from http://mochi227.blog.jp/archives/5050177.html .
1. Install the locale ja_JP.utf8 to the server.
1. At the beginning of your PHP code, add
setlocale(LC_CTYPE, 'ja_JP.UTF-8');