The world of Earth-land is home to numerous guilds where wizards[a] apply their magic for paid job requests. Natsu Dragneel, a Dragon Slayer wizard from the Fairy Tail guild, explores the Kingdom of Fiore in search of his missing adoptive father, the dragon Igneel. During his journey, he befriends a young celestial wizard named Lucy Heartfilia and invites her to join Fairy Tail. Lucy forms a team with Natsu and his cat-like Exceed partner, Happy, which is joined by other guild members: Gray Fullbuster, an ice wizard; Erza Scarlet, a magical knight; and Wendy Marvell and Carla, another Dragon Slayer and Exceed duo. The team embark on numerous missions together, which include subduing criminals, illegal dark guilds, and ancient Etherious demons created by Zeref, a wizard cursed with immortality and deadly power.
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.
After Natsu returns one year later, Fiore is invaded by the Alvarez Empire, a military nation ruled by Zeref, who intends to acquire Fairy Heart, a wellspring of infinite magic power housed within Mavis's equally cursed body preserved beneath Fairy Tail's guildhall. While battling Zeref, Natsu is informed of his own identity as both Zeref's younger brother and the true incarnation of E.N.D. (Etherious Natsu Dragneel), whom Zeref resurrected as a demon with the intention of being killed by him. When Natsu fails to do so, Zeref absorbs Fairy Heart from Mavis in a bid to rewrite the present timeline with one where he might prevent his own curse and Acnologia's rise to power. After Natsu defeats Zeref to stop the drastic changes to history his actions would create, Mavis lifts her and Zeref's curse by reciprocating his love, which kills them both.
Meanwhile, Fairy Tail and their allies detain Acnologia within a space-time rift created by the use of Eclipse, Zeref's time travel gate. However, Acnologia escapes while his disembodied spirit traps all of the present Dragon Slayers within the rift to maintain his godlike power. Lucy and the other wizards across the continent immobilize Acnologia's body within Fairy Sphere, while Natsu accumulates the other Dragon Slayers' magic and destroys Acnologia's spirit, killing him and freeing the Dragon Slayers from captivity. The following year, Natsu and his team depart on a century-old guild mission, continuing their adventures together.