Akuma to Tsuki no Yoru

Kyouko lives a solitary life, with her parents frequently absent and no close friends. One day, she encounters Lucifer, who identifies himself as the Prince of the Underworld, in a garden. After Kyouko saves him, he declares his intent to claim her as his wife. Meanwhile, Ishii-kun, the boy Kyouko once confessed to, unexpectedly begins pursuing her himself.