Zatch Bell!

Zatch Bell! is a Japanese manga series written and illustrated by Makoto Raiku. It was featured in Shogakukan's Weekly Shōnen Sunday between January 2001 and December 2006, concluding with 323 chapters compiled into 33 volumes. The story follows the title character Zatch Bell, a mystical being called a Mamodo, who is partnered with Kiyo Takamine, a 14-year-old schoolboy, in a once-a-millennium tournament on Earth that determines the right to rule the Mamodo world as king. During their adventure, Zatch and Kiyo encounter and battle various Mamodo and their human counterparts, as well as meet allies who aid Zatch in his quest to become a "kind king."