TRINITY SEVEN

Main male protagonist Kasuna Arata finds his world turned upside-down one morning when a magical disaster known as a "Breakdown Phenomenon" destroys his hometown and claims the life of his childhood friend. After receiving a Grimoire (book of spells) and a sudden encounter with a Mage sent to destroy him, he decides to join forces and enlists in a magical school charged with training magicians to deal with these disasters. Now enrolled and underway with his training, he finds himself butting heads with an organization out to destroy the world, a harem of deadly magicians at his back and his new-found powers threatening to destroy him while the world hangs in the balance.

Synopsis from Anime News Network