Set these properties in messages/webclient_ja_JP.properties and log into Alfresco with the ja_JP locale:
Those escaped characters appear to be normal Japanese characters as verified by placing into a JTextField.
1. Logon as Administrator.
2. Click "Company Home".
3. Click "More Actions->Manage Content Rules".
4. Click "Create Rule" button.
5. Selete an item from "Selete Condition" dropdown list.
Garbage is displayed in the button text as shown in the attached file.