Zatch Bell!

Legend of Kaguya. Gash's Summer Festival. Girl Who Returned to the Moon. (3x22)

Air date: Sep 04, 2005

Zatch and Ponygon are taken to a festival by Kiyo's mother. Once there, Zatch separates from them and meets up with a rich girl named Natsuko. Natsuko snuck away from her bodyguards in order to enjoy the festival.