WorldEnd: What do you do at the end of the world? Are you busy? Will you save us?

500 years have passed since the humans went extinct at the hands of 'Beasts'. The surviving races now make their homes up on floating islands, out of reach of most Beasts.
Only a small group of young girls, can wield the ancient weapons needed to fend off invasions from these creatures. Into the girls’ fleeting lives, enters a young man named Willem who lost everything in his final battle 500 years ago, the last living human awakened from an icy slumber.
He takes refuge on the floating islands, living in fear of the Beasts below. One day, he is tasked with being a weapon storehouse caretaker. But he soon realizes that these weapons are actually young Leprechauns who have no regard for their own lives. Among them is Chtholly.
Willem becomes something of a father figure for the young Leprechauns, supporting them in any way he can. He, who once fought so bravely on the frontlines, can now only hope that the ones being sent to battle return safely from the ones who destroyed his kind.