Magical Girl Raising Project, Vol. 15 (light novel) - Asari Endou - Bog

"Still stuck on the island without their magical powers, the heirs of the great mage and their magical-girl companions are in a panic. To leave the island, they must defeat the powerful goddess who has been slowly killing them off one by one. The survivors continue to fight despite their struggles...but who is controlling this goddess, and for what purpose?" --