Anisphia, a princess who has retained her memories from her previous life, has spent her nights doing some kind of shady research to fulfill her dream of using magic to fly. One night, she takes a test flight with her special witch's broom, but crash-lands in the middle of the noble academy's soirée. There, she sees Prince Algard publicly breaking off his engagement with the duke's genius daughter, Euphyllia...

After Euphyllia's engagement is annulled in front of her peers, Anisphia swoops in and carries her off. She returns to the palace and tells both girls's fathers that she wants Euphyllia to be her assistant, in hopes that it will restore the humiliated Euphyllia's honor. Thus the two of them begin to live together in a bizarre new arrangement...

Euphyllia is sick with fatigue from dealing with her new and unfamiliar lifestyle, but with Anisphia's gentle nursing and warm words, she quickly recovers. Ilia tells Euphyllia about her own past and Anisphia's true intentions, finally giving Euphyllia an idea of who she should strive to be. But then an unexpected urgent message arrives from the adventurers' guild...

After obtaining the dragon's magicite, Anisphia and Euphyllia visit Tilty, Anisphia's friend and research partner, in hopes of developing new technology with it. Anisphia is giddy with excitement, but then she receives word of the continuing investigation into the annulment of Euphyllia's engagement...

Euphyllia watches the battle between Anisphia and Algard grow increasingly intense as she frantically works to heal Lainie and Ilia. Anisphia struggles against Algard's new vampiric powers, but she makes up her mind to take her younger brother's life if it means stopping his evil deeds. The love- and hate-filled battle between brother and sister—prince and princess—nears its end...

With Algard gone, Anisphia is the only one left to succeed the throne, so she begins acting as a future queen should. Euphyllia makes up her mind to support Anisphia as her assistant and subject, but when she sees the lab all cleaned up and Anisphia forcing herself to smile, her heart wavers...

Meeting Lumi, a spirit contractor, has solidified Euphyllia's determination to be the next monarch. Her only wish is to preserve Anisphia's dream and her smile, but there is a hidden truth behind the spirit contract. When Anisphia learns what it is, she's unable to bear it and runs out into the icy rain...

"I don't want to let you become queen." "I don't want to let you give up everything." While Ilia and Lainie watch with bated breath, Anisphia and Euphyllia confront each other, each with her own conviction. Each one cares too much for the other to back down. When Anisphia strikes with all her strength, Euphyllia strikes with all her soul. Who will win this duel?