This is a really interesting story, about a real life monk, who started out as a retainer for his Samurai Lord, and ended up getting into a fight with him over a woman and killing him,
and then later after being a thief and a highwayman (robber) ended up becoming a monk, and spent his life looking for a way to pay back the harm he caused by doing good.
He ended up finding a town where there was a treacherous mountain crossing, where people were dying every year, and he went about single handedly digging a tunnel through it as his Buddhist practice.
The townspeople jeered him, then were inspired and encouraged him, then joined him to help him, then gave up seemingly thinking it impossible as a task, then joining again, then giving up, and all the while this monk kept working on it.
Later, the son of the lord he had slain years ago, who had spent years looking for this monk to kill him to exact vengeance, found him, and was persuaded by the town to let him finish, as at first, they defended the old monk saying no way could he kill him, but the monk said, no, I did this, it is my consequence, so the villagers persuaded the samurai to let him finish his tunnel first since it was his life's work.
The son of the lord agreed and since it was taking a long time, (some years) decided it would go quicker (and he could kill the monk sooner) if he helped the monk dig.
So they dug side by side, and eventually the son began to realize he'd spent years with anger and looking for vengeance, and wasted his life.
Eventually they became in training together, and when they burst through the wall, they both cried tears of joy and love for each other.
The tunnel is still in Japan to this day, and has been widened, with a modern road going through the side.
The original tunnel can still be seen and saved untold lives.
It's a really, wonderful, inspiring story.
And one of my very favorites.