Radiant Vol. 5 (manga)

The world is overrun with monsters called Nemeses--and a young boy infected by one will stop at nothing to defeat them all!

Evil creatures called Nemeses fall from the skies and the only ones who can fight them are Wizards--infected ones who survived a Nemesis's corruption. Seth, one of these survivors, vows not only to fight the Nemeses, but to find their mythical nest, Radiant, and destroy it!

Having escaped Rumble Town, Seth, Doc and Mélie are back at the Artemis Institute. With Alma's help, Seth learns more about his mysterious brother Piodon. But as much as Seth would like to stick around and learn, the search for Radiant has already been put off for too long, so Seth and his friends head for the island continent of the Wizard Knights. There, he discovers a world that's completely falling apart!