Maria calls on a devil to save the life of her beloved stepbrother, Hikaru. The devil that appears is an overwhelmingly beautiful man with black hair and black eyes. Given the name "Kuroki", the devil grants Maria's wish, but in return she must have sex with him 666 times! Maria is subjected to countless hot and heavy nights. And then, even Hikaru begins to be seduced by the ways she's changing… This is a story about sweet and sexual love!