Ninja often disguised themselves as servants on official errands or concealed themselves in cargo boxes to infiltrate the castle front gates undetected. The alternative was the arduous scaling of walls in the dark to breach the castles fortifications.
The castle base of steep interlocking boulders, nicknamed the musha-gaeshi (warrior-stopper), resisted common attacks by enemies of the castle. Yet, the gap between the stones provided tiny unintentional handholds for the ninja.
Many tools and climbing equipment were thus created to ensure safe and easier breaching of the castle foundations.
The Grappling Hook
Used to scale castle foundations, the grappling hook was among the six primary tools of the ninja. When climbing, the grappling hook would be struck into wall crevices to enable the ninja to grip the surfaces securely. Records in the Ninpiden Manual suggests that a larger grappling hook existed and was used to destroy enemy structures.
The Grappling Rod
Constructed by tying one end of a rope to the grappling hook and pushing the other end of the same rope through separated sections of bamboo, the grappling rod was an extension of the grappling hook.
To use the grappling rod, the rope was pulled tight to compress the individual sections of bamboo into one solid pole. The grappling rod would then be used to reach crevices (or hand-holds) that were out-of-reach. When the rope was slackened, the sections of bamboo separated. This enabled the grappling rod to be dismantled for storage.
The 3 Foot Piece of Cloth
Every ninja carried a multipurpose 3 foot piece of cloth. This was either tied around the waist or kept inside the clothing. Where the rope fell short, the cloth would be used to extend the length of the rope. The cloth is also used to conceal the head and face or worn as a head band.
Another equipment obviously purposed at climbing over obstacles is the ladder. A variety of ladders existed, all of which were constructed for convenient storage; being fold-able,extendable, or easy-to-dismantle.
Where the crevices between the boulders were too tiny for the fingers, tools such as the shikoro, kunai and kasugai were used as shims. Interestingly, for overcoming low walls, the ninja would lean their sword (scabbard down) against the wall, step onto the hilt and climb over the wall. Once over, the sword would automatically go over the wall because the scabbard was tied to the ankle of the ninja.
These climbing tools introduced enabled the ninja to overcome many structures and walls. They increased the survival rate of the ninja and allowed for tactical storage while on the move.