A very common trope in the accounts of the origins of traditional Japanese martial arts goes as follows:
According to the Takenouchi Keisho Kogo Den . . . Takenouchi Hisamori retired to the mountains near the Sannomiya shrine to train his martial skills. He practiced there for six days and six nights, wielding a bokken (wooden sword) two shaku and four sun in length (about 2 ft. 4 in. or 72 cm), a relatively long weapon for his purportedly short stature. On the sixth night he fell asleep from exhaustion, using his bokken as a pillow. He was awakened by a mountain priest with white hair and a long beard who seemed so fearsome to Hisamori that he thought it must be an incarnation of the avatar Atago Gongen. Hisamori attacked the stranger, but was defeated. The priest said to him “When you meet the enemy, in that instant, life and death are decided. That is what is called hyōhō (military strategy).” He then took Hisamori’s bokken, told him that long weapons were not useful in combat, and broke it into two daggers one shaku and two sun long. The priest told Hisamori to put these in his belt and call them kogusoku, and taught him how to use them in grappling and close combat. These techniques became called koshi no mawari, (around the hips). The priest then taught Hisamori how to bind and restrain enemies with rope, using a vine from a tree. Then the priest disappeared mysteriously amidst wind and lightning. – Wikipedia entry Takenouchi-ryū (with several grammatical corrections by this author)