Of course, the reality was less exciting, but the myth is a lot more tempting, so maybe it doesn't even matter what is myth and what was reality. Nevertheless, because of their notoriety, the ninja warriors are today one of the images defining Japan, and they were even officially selected to promote tourism in Japan...
EXIF info:
Nikon Df
Lens: 24-70mm F/2.8G
Focal Length: 62mm
Aperture: F/5.6
Shutter Speed: 1/160s
ISO Sensitivity: ISO 320