Choujin Gakuen: Konton Mouryou Seishun Jihen

In a far place in a far country there’s a mansion where a demon girl lives. One day there was a huge storm outside so in order to protect himself from the storm a mysterious boy named Adam enters the mansion. And so they meet... the little demon girl and the mysterious boy that looks like a shinigami, both outcasts in the human world, decide to create a school for monsters together!

(Source: Easy Going Scans)