Here's why:
* Magical Elements: The story features elements of magic, such as the talking mice, the enchanted soup, and Despereaux's ability to understand and communicate with other creatures.
* Fictional World: The story takes place in a fictional world with a medieval setting and its own set of rules and customs.
* Fantastic Creatures: The story features fantastical creatures, like mice that can talk, wear clothes, and have human-like personalities.
While it's a children's book, "The Tale of Despereaux" contains elements that make it fall under the genre of fantasy.