After several adventures, Natsu and his companions find Zeref living in isolation on Fairy Tail's sacred ground of Sirius Island, where he expresses a desire to die for the atrocities he has committed. A battle over Zeref ensues between Fairy Tail and the dark guild Grimoire Heart, which attracts the attention of the evil black dragon Acnologia. The Fairy Tail wizards survive Acnologia's assault when the spirit of their guild's founder and Zeref's estranged lover, Mavis Vermillion, casts the defensive Fairy Sphere spell that places them into seven years of suspended animation. Later, Fairy Tail wages war against the Etherious dark guild Tartaros, who aim to unseal a book believed to contain E.N.D., Zeref's ultimate demon. When Acnologia returns to annihilate both guilds, Igneel – revealed to have sealed himself within Natsu – emerges to battle Acnologia, only to be killed in front of a helpless Natsu, who departs on a training journey to avenge Igneel.