Five hundred years have passed since the humans went extinct at the hands of the fearsome and mysterious ‘Beasts’. The surviving races now make their homes up on floating islands in the sky, out of reach of all but the most mobile of Beasts. However, this new safe haven Regul Aire has a dark secret behind it. Only a small group of young girls, the Leprechauns, can wield the ancient weapons needed to fend off invasions from these creatures. Into the girls’ unstable and fleeting lives, where a call to certain death could come at any moment, enters an unlikely character: a young man who lost everything five hundred years ago, the last living human awakened from a long, icy slumber. As he struggles to come to terms with his accursed fate and find his place in this hostile new world, he becomes the father that the girls never had. Together, through their everyday interactions in the ‘orphanage’, they gradually come to understand what family means and what is truly worth protecting.