How is the book set up as a fantasy in the first chapter?

Artemis is a twelve-year-old genius who has taken a trip to Ho Chi Minh City. There he meets a man who sends him to a sprite who has the fairy Book. The story begins in the dawn of the twenty-first century. Given these facts, the reader can assume that the book will be fantastical. The twelve-year-old is a criminal mastermind after all who intends on stealing from the fairy world.