From Aerandria Scans:

The beautiful and mysterious "magamono" have been living quietly in their mansion until its heir, a boy called Momo, takes possession and starts wreaking havoc in their peaceful world. They don't know what to make of him, but neither does he, since they're not human and by far not what he expected. What are the "magamono," really? And what past does Momo's attitude hide? And what fun is about to ensue until they learn to live together?!