FAIRY TAIL Vol 52

From the Kodansha edition

After Fairy Tail’s revival, Natsu and his friends learn the reason behind the guild’s disbandment and Makarov’s disappearance. In order to protect this beloved family of his, Makarov had set out on a journey to the Albareth Empire, where mighty magical forces rule and where he vanished without a trace. Now, Erza must call together a group of special wizards for a secret mission­ to rescue Makarov! However, their path is blocked by the Twelve Shields guarding its emperor: A terrifying unit of super-powered wizards called Spriggan 2. What's more, in the heart of it all lays Fairy Tail's most hidden secret...!

Source: Anime News Network Encyclopedia