Imsk is a planet whose residents have the ability to shrink. Their race didn't originate on Imsk, but were descendants of a Krill Colony. They arrived on Imsk almost a million years ago. On the eleventh year, the whole world began to shrink. For fifty days the planet continued to dwindle smaller and smaller, but the residents of the world remained "giants." One of the colonists was able to discover a peculiar energy from radioactive boulders, and he turned that radiation on the others. This altered their genetic structure and the people began to shrink. From then on, the ability to shrink became a hereditary trait passed down from generation to generation..
Although a member of the United Planets, there is a strong separatist movement that has at times controlled the government and withdrawn from U.P. membership. Imsk and Braal eventually went to war, with Imsk winning after the detonation of a magnetic bomb at Venado Bay that devastated the magnetism-controlling Braalians and cost Rokk Krinn, formerly Cosmic Boy, his powers.