Black Heart is the 426th chapter of Hiro Mashima's Fairy Tail. Natsu and Lucy discuss the contents of the request that Natsu has taken from Rogue, and Lucy reveals that Avatar is a cult worshipping Zeref. Natsu is prepared to attack them, while also explaining what Future Rogue told him about Gray, noting that they might encounter him not as a friend, but as an enemy. Meanwhile, in Avatar's headquarters in Mikage Forest, the cultists prepare for a purification ritual, while one of their members, Jerome notes they have been infiltrated by the Magic Council. Elsewhere, the Magic Council Custody Enforcement Unit advances upon the base of Avatar with a goal to capture every cultist, led by Gajeel, with Panther Lily also being the member.