Mint is a young girl who also happens to be the princess of the world of dreams and magic. The natural environment of her world is only a reflection of the dreams of the people on Earth. It is now in danger as people lose faith in their dreams and let darkness enter their hearts; this is causing the environment of Mint's world to wither and die.
On her 12th birthday, after a gala celebration with her father the King and her mother Queen Lime, she agrees to go to the world of humans to try to preserve people's hopes and dreams, and to prove that she has the qualities necessary to be a wise ruler. However, when Mint discovers that all of the flowers of the rainbow garden are blue (the color of sadness), she knows her task will not be an easy one.
Mint's father arranges for her to stay with his sister, Mint's Aunt Herb, who runs a gift shop on Earth called "Happy Shop". Mint is also allowed to choose two best friends who will share the secret of her true identity. She chooses a young boy named Plum and a young girl named Nut, because when she arrives on Earth, she realizes her father forgot to give her her aunt's address, and they help her find the shop. Her pet parrot Waffle goes with her as her mascot and to try to keep her out of trouble.