A samurai warrior slew his master in a fit of rage. He repented immediately but the deed was done and he knew that if he was caught he would be put to death. So he fled and reached a remote village that was separated from the rest of the world by a mountain. The path across the mountain was narrow and treacherous. The murderer decided to atone for his sin by single-handedly cutting a road through the mountain to end the isolation of the village. He worked from dawn to dusk and in four years had penetrated halfway into the mountain. One morning when he was hard at work in the tunnel, a young man called out to him to come out. He was the son of the man who had been murdered. He wanted revenge.
The samurai said that he surely deserved death, but asked him to wait until the tunnel was completed. The young man agreed to wait. He watched fascinated as day after day the samurai labored at a seemingly impossible task.
He saw the samurai working hard. The young man began to develop respect for his enemy. Eventually he started helping him. Years passed and then one day the two men broke through to the other side. The isolation of the remote village finally came to an end.
The Samurai agreed to die now. The young man said that earlier he was his enemy but now he is his teacher and he had learnt a lot from him in the past few years. So he did not kill him and went away.