Jujutsu is an ancient system of fighting arts based on the principle of yawara, or pliability, going back to pre-history in sumo wrestling at Shinto shrines.
The yawara strength of jujutsu is said to be like that of bamboo: it bends to force, but it won’t fall over and it will spring back with power.
Part of this is the nature of the stalk of bamboo, segmented and pliable.
But the most important part of bamboo’s strength is the massive root system connecting all the stalks on a wild tangle of criss-crossing roots, all sending out feelers in six directions to grow thick and hardy and dig into the dirt like a burrowing dragon, supporting each stalk with a broad system of highly flexible fibers all clutching the mass of the earth.
As a long-cultivated protege of Jigoro Kano, Minoru Mochizuki understood both judo and aikido as sub-classes of jujutsu.
He called his master text Nihon Den Jujutsu: kuro obi aikido (Japanese Tradition Jujutsu: black belt aikido).