A mature and somewhat philosophical girl Arisa encounters Magnus, a white horse that speaks Japanese. When Magnus asks her to transform into a magical girl, Arisa, fearing the disruption of her normal life, initially flees. However, when Arisa and Magnus become targets of the evil organization Greed, she is forced to transform into the magical girl Artemina and confront the organization's attacks. As Greed threatens to disrupt the world, Arisa, now Artemina, struggles with the erosion of her everyday life. Despite facing personal challenges, Arisa develops a sense of duty as Artemina and grapples with the choice between despair and a peaceful everyday life in the face of an uncertain future.

[Translated from the official site]