Index: branches/Ver2.4/xpressme_integration_kit/wp-content/plugins/xpressme/xpressme.php
===================================================================
--- branches/Ver2.4/xpressme_integration_kit/wp-content/plugins/xpressme/xpressme.php	(revision 792)
+++ branches/Ver2.4/xpressme_integration_kit/wp-content/plugins/xpressme/xpressme.php	(revision 794)
@@ -82,4 +82,20 @@
  	}
 }
+
+// enable multibyte username
+if( ! function_exists( 'sanitize_user_multibyte' ) ){
+	function sanitize_user_multibyte($username, $raw_username, $strict){
+		if ($username == "" && $strict){
+			if ($raw_username == ""){
+				return $username;
+			} else{
+				return sanitize_user($raw_username, false);
+			}
+		} else {
+			return $username;
+		}
+	}
+}
+add_filter('sanitize_user', "sanitize_user_multibyte" ,10,3);
 
 add_action('admin_menu', 'my_plugin_menu');