Also known as Magical Girl Flaming☆Star, Mahou Shoujo Flaming☆Star. Manga by Kenji Saito and Shouji Sato.
During a field trip with their middle school classmates, childhood friends Kaguya and Himawari are abducted by the secret society Millennium. The evil organization is notorious for the havoc it's wreaked, but it's possible they're not the bad guys. After Kaguya gets a glimpse behind the curtain, everything starts to change, and she becomes privy to the truth underneath the world she lives in. Now that she's bestowed with the power to transform into a magical girl and must choose a path.