Light Novel Volume 15

Summary
Thanks to Nanahoshi, Rudeus and his companions are off to visit Dragon King Pergius Dola. Using teleportation they were transported to a floating citadel, where Pergius and his familiars awaited them. Their days at floating citadel continued and they learned more about summoning techniques, but soon a great problem appeared. Nanahoshi was dying! Person without any magic power will have its body corrupted by magic and slowly die, naturally magical treatments were ineffective. Only solution was to contact an Immortal Demon who has seen the disease in the past and will probably know the cure for it. Once again, Rudeus returned to the Demon Continent in his search for Demon Empress Kishirisu who knew what the cure is, in the process he managed to incur the wrath of the Demon Lord Atofe. However, everything ended well, though they almost died while fighting Atofe and they managed to cure Nanahoshi.