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