Bucky, the protagonist of the story, is an ordinary boy living in the First World. He harbors a single, modest ambition: to dominate the world (meaning the entire planet). He is very certain of this goal and would certainly die to achieve his dream. One day, he meets Spark, the Great Child of Primas (World One). Spark is known as the strongest Great Child across all worlds and is searching for a successor. After finding Bucky and speaking with him briefly, Spark chooses Bucky as his successor for no apparent reason. Bucky has just become a Great Child and wins the company of Jibaki, the spirit of the First World.