Once upon a time, there was a man who lived alone and caught fish every day. One day, he caught a golden fish that turned into a beautiful woman. They got married with one condition: he must never tell anyone that she was once a fish. They had a son, who was lazy and ate a lot. One day, the man got angry and shouted that his son was a son of a fish. The woman heard it and was very sad. She and her son disappeared, and the land sank into a lake, which is now called Lake Toba.
Who was the main character in the story?