Kiyo Takamine is an average 14-year old genius. He was being bullied at school, so he stopped going to school. This all changed the day he met Zatch Bell. Zatch taught Kiyo the importance of friendship and helped him make his first real friend, Suzy Mizuno. Later, Zatch, who had amnesia, learned that he is a mamodo ("demon"). Every 1000 years, 100 mamodo children are sent to Planet Earth for a battle to decide King of Mamodo World ("Demon World"). Each mamodo partners up with a human who is able to read their book. Using the power of the book, the humans can cast powerful spells for their mamodo by using their own emotions as an energy source. If a mamodo's book is burned, he or she is eliminated from the battle and sent back to the Mamodo World. The last mamodo standing in the Human World becomes the next King.