an external output unit configured to output {TAIL ~ a signal} of {HEAD ~ contents} including an image to said second wearable display, and 
an external output unit configured to output { TAIL ~ a signal } of { HEAD ~ contents } including an image to said second wearable display , and
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH