Originally, Tube was peaceful underground empire ruled by the Igum family who slain a dangerous monster terrorizing their realm called Lethal Doggler. However, the Doggler had a child who infiltrated the Igum kingdom as the usurper Zeba who corrupts the land into a violent kingdom where strength rules all while enslaving the underground humans. However, Zeba learns that his downfall will be caused by the Igum family's two surviving members, twin sisters Iaul and Igum, and decided to keep the two apart to maintain his dominion as he turns his attention to the surface world and used the former a spy. But her falling in love with Takeru and attempt of warning him of the invasion gave him a reason to permanently separate the twins by sealing Iaul in ice while Igum grew to hate her sister for dishonoring them and takes out her rage on Takeru as he joins the Maskmen to fend off Tube's forces.

Later, fed up of Baraba's failures, Zeba gives him a last chance to destroy the Maskmen. But he allies with Kiros who betrays him and his servant Oyoboo refusing to help him, Baraba will be finally killed by Takeru.