Samebito

The is a creature that appears in "The Gratitude of the Samebito", a short story by Lafcadio Hearn. It is described as a humanoid with inky black skin, emerald green eyes, a face like a demon's, and a beard like a dragon's.In the story, a man named Tōtarō meets the Samebito one day on a bridge. Although frightening, the creature turns out to be a gentle being who, as punishment petty fault, has been expelled from the sea by his former employer, one of the eight great Dragon Kings of the ocean. Tōtarō takes pity on the creature and allows it to live in a deep pond in his garden. Meanwhile, Tōtarō has been seeking a bride, and eventually falls in love with a beautiful woman he sees at a female pilgrimage at Mii-dera. He becomes deathly sick with grief, however, on learning that her family requires a betrothal gift of ten thousand jewels for her hand in marriage. When the Samebito learns that his master is on his deathbed, he begins to cry tears of blood which become precious rubies when they hit the ground. Through the Samebito's tears, Tōtarō eventually wins the hand of the woman with whom he is infatuated. When he has finished weeping, the Samebito is also pardoned by the dragons, and the story ends happily.
See more at Wikipedia.org...

[Japanese] A black monster with green glowing eyes and a spike beard from Japanese mythology. On the Long Bridge the monster encountered the hero Totaro, but instead of attacking him, the monster entreated him to give it food and shelter. It turned out that the sea-king had expelled it from the ocean. Totaro took the monster with him and gave it a lake near his own palace where he fed it. Some time later, Totaro fell in love with the beautiful Tamana and intended to marry her. Tamana's father however, had set the bride price at 10,000 precious stones. Unable to come up with such an immense fortune, Totaro went home and lay ill until he was dying. When Samebito learned of what happened to its benefactor, it shed tears of sadness until the monster discovered that its tears had turned into pearls, rubies and emeralds. With these precious stones Totaro was able to pay the bride price and marry the lovely Tamana.