Who is Magistrate Tiger/Green Tiger from Where the Mountain Meets the Moon and what is their importance?

Magistrate Tiger was a ruler of the land in which all the main landmarks (save the moon) were located over a century ago. He was a cruel ruler who often carried out ruthless threats and punishments on those who did not deserve it. It was he who had the painting commissioned that created Dragon and it was he who tore a page out of the Old Man of the Moon's Book of Fortune. Further, it was Magistrate Tiger's angry spirit that was reincarnated into Green Tiger.