The Dark Academy of the Dead

(from ebookjapan):
Risa, who wants to go to Tokyo to become an idol, finds a strange advertisement in an entertainment magazine. It says that any ugly girl can become beautiful if she enrolls in "Hikari Academy". Desperately trying to persuade her parents to make her dream come true, Risa enrolls in the school. However, she finds an unimaginable and unexpected horror and shudder awaiting her there.