Teenage math whiz Kenji Koiso agrees to take a summer job at the Nagano hometown of his crush, Natsuki. When he arrives, he finds that her family have reunited to celebrate the 90th birthday of their matriarch. His job: pretend to be Natsuki's fiancé. Meanwhile, his attempt to solve a mathematical equation causes a parallel world's collision with Earth.
A young girl had her voice magically taken away so that she would never hurt people with it, but her outlook changes when she encounters music and friendship. Will Naruse be able to convey the anthem of her heart?
The film revolves around a mysterious girl named Éclair who appears before Fairy Tail, the world's most notorious wizard's guild. She lost all of her memories, except for the imperative that she must deliver two Phoenix Stones somewhere. The stones may spell the collapse of the magical world, and Natsu, Lucy, and the rest of the Fairy Tail guild are caught up in the intrigue.
