In a city threatened by the evil organization called Hamelder, they roam the streets at night, kidnapping women. To protect the city, a group of girls, led by the magical girl, Frostia, who is also known as Hiyama Sumire, emerges as the Magic Battle Princesses.
Among the ordinary girls living in the city is Himesato Rin. She’s a shy and plain girl, but she’s troubled by her slightly larger breasts than others. One day, as she walks home, she gets attacked by Hamelder’s soldiers. In her moment of desperation, Frostia comes to her rescue, revealing her true identity. Rin admires Frostia’s bravery but worries about her battle. Seeing Frostia facing danger sparks a fire of justice within Rin. “I want to become a Magic Battle Princess too!” Filled with determination, Rin decides to become a Magic Battle Princess herself, ready to fight alongside Frostia against Hamelder’s evil plans.