Zatch Bell 2 [Zatch Bell Makai]

100 demon children fought to determine the new king of the demon world. Once the war ended, the new king was crowned, and the demon world was at peace... or so you thought! The shocking reality of the current-day demon world is now revealed—and deep in the maw of despair, three demon children make a dangerous gambit. (Source: Birgdin Board, translated)