Renaming folders in Japanese

I would like to rename the inbox, outbox, sent items and deleted items folders in our english version of Windows mail into Japanese, since we are using Mail mainly for Japanese language. I can do this with other boxes using the IME editor (right click/rename and simply type names in Japanese) but there is no "rename" option available when I right click on these 4 folders. I tried to rename the relevant folders in Japanese in windows explorer by going to c/users/me/app data/local/microsoft/windows mail/local folders and renaming the relevant folders. It works fine but the relevant folders still do not display the Japanese language name when I open the mail program. Appreciate any advice you might have. Thanks in advance.