Kyrie Florian makes a daring attempt to save her father and her dying home planet of Eltria, but her childhood friend Iris betrays her. Unfortunately, the power she has gained from Nanoha Takamachi and the other Earth protectors cannot be used to aid her father. Iris abandons Kyrie, having obtained what she needed to seek revenge on Yuri Eberwein, a powerful entity that lies dormant on Earth. Nanoha and her comrades must confront troublesome Iris to uncover the truth and end the battle between her and Yuri. Nonetheless, an even greater danger lurks in the shadows during the intense battles. Regardless of the challenge, Nanoha remains steadfast, using her magic to assist those in need without hesitation.