Konjiki no Gash Bell!!

Synopsis

Megumi Oumi, a famous singer, is going to make a show in Mochinoki Town. As Suzy can take friend along with her to it and Marylou is unable to do so, Kiyo is invited by her and accepts the invitation. However, Zatch also wants to go there but isn't old enough. Meanwhile, Megumi and her mamodo Tia discuss about both the show and running from other mamodo due to their spells being too weak. As Zatch manages to sneak into the building, another mamodo duo appears to fight Tia, which is revealed to be Maruss, an old friend of Tia's that became her biggest nightmare in the human world. Tia and Megumi hold off the pair until Zatch and Kiyo return to help.

(Source: Zatch Bell Wiki)