Kyrie Florian, along with her parents and older sister Amitie, calls the dying planet of Eltria their home. The Florians are scientists, tirelessly working to discover a protocol that could save their planet. However, the situation worsens when Kyrie's father contracts a deadly illness, forcing her family to abandon their quest in search of medical treatment. Despite receiving therapy, Kyrie's father's prognosis for survival remains bleak. Driven by her unwavering loyalty to her family and home, Kyrie embarks on a dangerous mission that opposes her sister's wishes. Leaving Eltria behind, Kyrie ventures into Earth to uncover a solution for her father's condition. She enlists the help of her childhood friend, Iris, and seeks the assistance of Earth's magical defenders, Nanoha Takamachi, Fate Testarossa, and Hayate Yagami. Kyrie knows that the key to her success rests with Nanoha and her team, and she's determined to acquire it, no matter what it takes. However, the guardians aren't easily swayed, and Kyrie must raise the stakes to appeal to them. Amitie learns of her sister's perilous escapades and appears on Earth, further complicating the already precarious situation.