Once, there lived an old woodcutter in the village of Motoda in Oki-no-kuni. One day, he went along the Yasunaga river to cut wood in the mountain above the waterfall. By mistake, the axe slipped from his hands and fell into the little round pool at the foot of the waterfall. Suddenly, waves began to stir up in the pool, a thick mist rose, and it became dark all around. The woodcutter saw something like a big black stick covered with thorns coming out of the water. Frightened, the woodcutter ran as fast as he could. A gentle voice called him from behind, “Old man, please wait a bit.” He looked around and saw a lovely damsel, as beautiful as a picture, standing at the waterfall. “I am Princess Yasunaga,” she said, “I have been living in this pool for ages. But some time ago, a huge crab came and started living here. He has been tormenting me day and night.”

Crab Pool and Princess Yasunaga
Princess Yasunaga then said to the woodcutter that when his axe dropped, it cut off one of the arms of that wicked crab, weakening his strength. So, he must have seen that big arm with thorns floating away. The crab groaned in pain and hid in a ledge at the bottom of the pool. She requested the woodcutter to let the axe fall again from the top of the waterfall. She handed him his axe. Afraid, he threw his axe from the top into the basin at the falls. “Money and fame and long life or whatever you ask shall be yours, even as you ask for it,” said the pleased Water Spirit, and she returned to the forest. After a few days, the villagers discovered the shell of a dead crab. Both its arms were missing which had been washed down to the mouth of the river at the sea. Since then the river is called Yasunaga River and the basin of the waterfall is called Crab Pool.