From Ainu Folklore
At the head of Japan there was a metal (i.e. very hard) pine tree. Now, the ancients, both noble and ignoble, came together and broke and bent their swords (upon that tree). Then there came a very old man and very old woman upon the scene. The old man had a useless old axe in his girdle, and the old woman a useless old reaping hook. So they caused the ancients to laugh at them.’ (That is, the Ainu laughed at the bare idea of such an old couple coming to render assistance.)
Even the ancients were unable to cut down that tree, so they said: “Old man and old woman, what have you come hither to do?” The old man replied, “We have only come that we may see.” As the old man said this he drew his useless old axe, and striking the metal pine tree, cut a little way into it. And the old woman drawing her useless old reaping-hook struck the tree and cut it through. There was a mighty crash; the earth trembled with the fall. Then the old man and woman passed up upon the sound thereof, and a fire was seen upon their sword-scabbards. The ancients saw this, and greatly wondered, and then they understood that it was Okikurumi and his wife.
Therefore the Ainu say: ‘Let not the younger laugh at the elder, for even very old people can teach their juniors a great deal, even in so simple a matter as felling trees.’ Also they say: ‘No not treat strangers slightingly, for you never know who you are entertaining.’ These strangers who appeared to the Ainu were no other than the great hero Yoshitsune (Okikurumi is his Ainu name) and his wife.
Source:
The Ainu and Their Folk-Lore, John Batchelor, 1901
Kotharian Lightning 