If they have no head you can try to shove a hard flathead to make a grove and screw them out, you can try with tweezers or worst case scenario, drill them out.
To remove stripped screws: If you can get at the screw heads try to grab a long-nose pliers and squash the screw head, then you can try to use a flathead screwdriver or by turning the pliers, if that you don’t have those tools you can try with the normal screwdriver and a rubberband in between.
Japanese cameras use JIS/JCIS (Japanese Camera Industrial Screws) screws not philips.