Most Millennium Godzilla films (1999-2004) are standalone reboots ignoring all previous films except the 1954 original. Tokyo SOS is the exception. It directly follows Godzilla Against Mechagodzilla . You need to know that Akane Yashiro (the female pilot) is traumatized, and that Kiryu (Mechagodzilla) has a soul—the bones of the original 1954 Godzilla.