Crimson Lunatics

Once, "Integral Sorcerian Academy", which teaches magical experts, experienced an incident called "the night of the red moon", where demons attacked the school. In order to contain the situation, an all-girl team "Anti-Spectre" was formed by the most prominent students and the demon who led the attack was sealed. Our protagonist is a freshman who passed the difficult general admission test in order to become a student at this school. He loses his life, while being caught up in the fight between anti-spectres and a demon, but is saved by the sealed demon Morpheris. The demon's deal in order for the protagonist to live, is to help in breaking her seal and corrupting the anti-spectre team to the pleasures of flesh. "Next until the moon turns red" is set as a deadline, and if the protagonist fails to accomplish the task, he will lose his life. [Translated from Getchu]