Megumi Ooumi is a 14-year-old pop star, and The Keeper Of The Book to a 6-year-old Mamono named Tio. She is often seen in video games or doing concerts, but despite all this, she remains a normal girl.

She has a very kind-hearted personality, and sees Tio like a little sister, often calming down her fits of rage and helping explain the world to her.

Megumi first met Tio when she found her injured on the docks. At first, Tio had kept harshly to herself when they'd first met, saying that Megumi would only get hurt helping her fight off Mamono. They eventually started to get along, and Tio came to trust Megumi.

After being helped by Gash and Kiyo, Megumi saw them as friends, like Tio, and swore that one day they would return the favor.

(Source: Wikipedia, Zatch Bell! Wiki, edited)