Akuma Ni Chic X Hack summary:

This is a fantasy love story about a demon princess who falls in love with a human boy. They exchanged a pact when he was young, and Giselle descends to the human world once again to convey her feelings. The target of her affections is a human boy, Shiina Ichiritsu. In order to get closer to him, she enrolls into his all boys' boarding school! But he's not how he was before at all!!!