Belgim E.O.

Belgim E.O, one of the Four Supreme Mamodo, and his present-day bookkeeper Dalia Anjé are confronted by Kanchomé and Parco Folgore and Kido and Dr. Riddles in the ruins. Belgim E.O. is very powerful, but easily appeased if he is entertained, although if he becomes bored, he gets angry and attacks.

Belgim is eventually defeated by Kido's most powerful spell, Mikor Ma Zegaruga, although Kido's own book is burned in the process. Belgim E.O. is later seen in the final chapter of the manga as a new student in Zatch's school of the same grade and classroom for a particular class.

(Source: Gash Bell Wiki)