When does Zatch Bell! return?

Zatch Bell! is a Japanese manga series written and illustrated by Makoto Raiku. It was serialized in Shogakukan's sh?nen manga magazine Weekly Sh?nen Sunday between January 2001 and December 2007. The series was later adapted into an anime television series produced by Toei Animation. Viz Media licensed both the manga and anime series for English-language localization in North America in 2005.
The story takes place during the modern times in which mystical creatures with supernatural powers called Mamodo descend to Earth from the Mamodo world. Every 1,000 years, one hundred Mamodo are sent to compete in a tournament for the kingship of their world. Each Mamodo carries a spell book that seals away their powers and requires a human companion to read aloud in order to cast them in the form of spells. Only one human is allowed to read from that Mamodo's book, whereupon he or she becomes its book owner[e] and partner.