Zen-Kai, the son of a Samurai, journeyed to Edo and there became the subject of a high official. He fell in love with the official's wife and was discovered. In self-defence, he slew the official. Then he ran away with the wife.
Both of them later became thieves. But the woman was so greedy that Zen-Kai grew dis-gusted. Finally, leaving her, he journeyed far away to the state of Buzen where he became a wandering mendicant.
To atone for his past, Zen-Kai resolved to accomplish some good deed in his lifetime. Knowing of a dangerous road over a cliff, causing the death and injury of many persons, he resolved to cut a tunnel through the mountain there.
Begging food in the daytime, Zen-Kai worked at night, digging his tunnel. When thirty years had gone by the tunnel was 2280 feet long, 20 feet high, and 30 feet wide.
Two years before the work was completed, the son of the official he had slain, who was a skilful swordsman, found Zen-Kai out and came to kill him in revenge.
"I will give you my life willingly," said Zen-Kai. "Only let me finish this work. On the day it is completed, then you may kill me."
So the son awaited the day. Several months passed and Zen-Kai kept on digging. The son grew tired of doing nothing and began to help with the digging. After he had assisted Zen-Kai for more than a year, he came to admire his strong will and character.
At last the tunnel was completed, and the people could use it and travel in safety.
"Now cut off my head," said Zen-Kai. "My work is done."