Tonga is tricky.  Well, not so much the country, but its postcards.  It attracts foreign manufacturers.  We cannot say that this unused card ever came close to Tonga, but subcaptioned “Niuafo’ou Philatelic Service & Tin Can Mail History” (whose history is easily Googled), we also cannot say that it did not.  It may have been made in the Czech Republic.  In any case, we are comfortable listing this card here.  Grade: 1