Mahou Shoujo Kazumi★Magica: The Innocent Malice

Kidnapped and stuffed into a trunk by an unknown assailant, teenager Kazumi bursts forth from the confines of the case to discover that she has been stripped not only of her clothes, but also of the memories of her life before the kidnapping. When she is recovered by a pair of schoolgirls, she doesn't recognize them as her best friends and roommates, Umika and Kaoru. As Kazumi tries to settle back into her normal life, she quickly realizes that her former "normal" was anything but!

(Source: Yen Press)