Rebirth

Ayumi Drevis is a regular middle school student with an incorrigible knack for causing trouble. But all that changes when she opens up a book and slips into the fantasy world of Rebirth, filled with magical creatures and foul-tempered humans, who are trying to take off her head!
Along the way, she and her friends are tasked with locating the three divine instruments and battling the evil forces known as "Nightmares," many of which were former children. By putting her life on the line, Ayumi must use every ounce of courage and face the demons that haunt her visions in order to save everyone and return home.