We know from ninjutsu texts that the shinobi took the matter of travel between and within provinces with dire seriousness. They were prescient enough to mask their identities with appropriate cover, making themselves appear on the well-trodden roads as common travelers, merchants, and monks, for the nature of their trade would espouse mortal danger if they were to be known for conveying communications against the lord of the region. This was, as related in a previous post on Tsugi Hikyagaku, a vital facet of ninjutsu that was coveted enough by opposing lords to the extent that they would employ their own shinobi to thwart the sour prospect of spies infiltrating their lands.
If the artificial veneer of the ninja was compromised, by peasant aid or the work of a military functionary, they would have found themselves in a difficult situation wherein pursuit by the enemy could become inevitable. So if a ninja was tailed by an enemy shinobi or perhaps a common foot-soldier, what might we expect him to do in effecting his good escape?
The resourcefulness of ninjutsu is vast, and so viable options were not constrained down to a mere handful. He might toss out thorny caltrops to attack the feet of those following; he could race away into the darkness and toss stones into nearby waters to evince an ostensible escape into shadowy their shadowy depths; he may even fix fuses to trees that would be lit in the darkness to confuse his tail; but the single technique we will address today would probably have been employed during the daylight hours to make cautious a single enemy whose mission was to track this spy who had been identified as such.
Ude Karami is described as the art of using one’s sword scabbard as a psychological deterrent against a follower. It is employed easy enough, or at least inasmuch as we can induce from the texts. The scabbard was tossed on the ground conspicuously so that when the tail came across it he could not help but raise his senses to the potentiality of an ambush. Meanwhile the evading shinobi was making good his escape.
Think about it. Try to envision a time when the common armaments were swords, bows and arrows, spears and pikes. To see a scabbard laying on the ground like this would have surely evoked at least a small measure of caution in whoever came across it. One can imagine this tactic could have been quite effective in affording the evading shinobi more time to create space between he and his adversary.