He is a prince from a kingdom in the Far East who decided to travel to Dunwyn in order to find Gummi Bears. After a long journey, he collapsed in the courtyard of Dunwyn Castle. He is received at the court of King Gregor, who is pleased to have a visitor from Asia come to Dunwyn, but says no reports have been made of Gummi Bears being seen in Dunwyn for 500 years. Cavin decides to inform Gruffi about this when he sees Prince Yen Moon holds a jade Gummi statue, which Zummi later says was a token from the Great Gummies. The Glen Gummies agree to meet Yen Moon, who asks for their assistance in banishing a dragon who has been wolfing down the crops in his kingdom. The prince is not seeking something for nothing, and agrees to solve a problem in Gummi Glen in exchange for their help. Prince Yen Moon fixes the broken air conditioning in Gummi Glen (by repairing a broken gear which powered a machine that circulated mountain air). Later, the Gummis travel to Yen Moon's kingdom, where they are amazed at seeing a kingdom where humans know about Gummi Bears and receive them as guests. The Glen Gummies decide to follow the same path as their ancestors and use strategy to foil the troublesome dragon.