Cinque Izumi makes a promise with his best friend Rebecca to go flower viewing during the last three days of Spring Break. However, while he is alone trying out some acrobatic moves in school, a dog appears and opens a magical portal while Cinque is in mid-air, resulting in him jumping through the portal with the dog. He arrives in the land of Flonyard, and is greeted by a beautiful girl, albeit with bestial features like dog ears and tail. The girl, who introduces herself as Princess Millhiore, requests for his assistance, which he agrees to and becomes the Princess' Hero, in order to drive away the forces of Galette which seeks to invade Biscotti.

Cinque learns from Millhiore how she used her stargazing powers to learn about him and why she chose him as her hero. Meanwhile, Leonmichelli confirms by using her own stargazing powers that an ominous fate awaits them.

Desperate to change Millhiore and Cinque's dreadful fate, Leonmichelli challenges Biscotti for another battle with each country waging their most sacred treasures on it. Millhiore reluctantly accepts the challenge, unaware of her true intentions.

The day of the battle comes and it does not take long for Millhiore to confirm her suspicions about Leonmichelli's behavior and she joins Cinque and Éclair to storm the fortress where Leonmichelli is stationed to confront her. Meanwhile, Brioche and Yukikaze feel that a strange presence is approaching.