This season has 39 episodes containing the "Tartaros" (冥府の門タルタロス編, Tarutarosu-hen) arc, which adapts material from the rest of the manga's 40th volume to the middle of the 49th volume, depicting Fairy Tail's battle with a dark guild of Zeref's demons who aim to resurrect E.N.D., their master and Zeref's ultimate creation.
While relaxing in their new bathhouse, the Fairy Tail women get a surprising, and not entirely welcome, visitor. Later, Natsu and Gray specifically get a job request from Warrod Seeken, 4th-ranked member of one of the Ten Wizard Saints. But what mission could a wizard of his stature have in mind for Fairy Tail?
As the Fairy Tail Mages arrive at the mysterious Sun Village, completely frozen, they get into a fight with the Hunters of Sylph Labyrinth. Meanwhile, a new threat, Succubus Eye, is also approaching the village, with Minerva as the new recruit.
As Erza is looking for a way to return to her original form, she is approached by none other than Minerva. Meanwhile, Natsu soon meets Doriate and his Magic, turning him into a child as well.
As Flare is fighting against the Hunters of the Sylph Labyrinth, along with Lucy and Wendy, Erza finds herself under Minerva's attack. Meanwhile, Natsu is still searching for the familiar voice, all the while Gray ends up encountering Doriate, falling victim to his Magic as well
Gray snaps out of the memories of Deliora, Moon Drip, and ice holding him back, and is ready to fight back. He asks Doriate whether he froze the Giants or not, before declaring his will to defeat him. Meanwhile, Lucy, Wendy and Flare, having defeated the Hunters, rush towards the Eternal Flame, worrying about their friends as well as the Giants at the same time. Happy and Carla are also in a predicament, as a Cyclops Monster roams the sky, scaring them into staying hidden.
As Natsu battles the formidable winged cyclops monster, Gray enacts his plan to melt the mountain of ice encasing the Eternal Flame... but does he end up extinguishing that along with it? Plus: the identity of the familiar voice that called out to Natsu, bringing him to the frozen Eternal Flame!
Natsu and the other Fairy Tail wizards help celebrate Flare's homecoming in the defrosted Sun Village. Meanwhile, Minerva returns to the Succubus Eye guild, only to find a member of Tartarus waiting for her. Later, the Fairy Tail wizards make it back to Warrod's house for rest, relaxation, and a revelation about his past!
The Magic Council is having a meeting about the mysteriously-disappearing dark guilds when they're attacked by a powerful force, the harbinger of the Tartarus threat that will derail Fairy Tail's recent relative peace and quiet.
The battle between Laxus and Tempesta ends with all the members of the Raijinshuu lying near death. Natsu and all the other Fairy Tail members want to avenge them, but Tartaros's whereabouts are unknown. Meanwhile, the demonic members of Tartaros begin to get intrigued with Fairy Tail...
Natsu foiled the initial attempt on Michello's life, but now he has to battle Jackal, one of the Nine Demon Gates, to keep the former Magic Council member safe. It's a hard fight, especially since Jackal has the power to make anything he touches (or that touches him) explode.
Natsu has a final showdown with Jackal, who turns himself into a human bomb at one point! Later, the other teams arrive too late, finding the other former members they're meant to protect already murdered by Tartaros...
Erza and Mirajane visit Crawford, the former Magic Council chairman, and fall into Tartaros's trap. And in exchange for information on Tartaros, Doranbolt frees all the members of Oracion Seis!
After breaking into the Tartaros stronghold, Natsu goes up against the foul Franmalth before getting an even chillier reception from another member! Meanwhile, the members of Oracion Seis are fighting for their freedom against Jellal, who tells them they're still slaves to darkness!
As Natsu and Lisanna plot their escape from the cell, Tartaros gains control of the magic weapon of mass destruction, Face. Levy tracks down the dark guild's location and it's closer than anyone expected, but before they can mount a rescue to save Natsu and the others, a mind-controlled Elfman activates a lacrima bomb at the guild!
Cana engineers a clever way to get everyone out of Fairy Tail moments before the headquarters is blown apart in a massive explosion. Inside the Cube, Erza turns the tables on Kyoka, but how does Erza's magic stand up against the power of Curses? And a sinister figure suddenly appears before the escaped Natsu...
The members of Fairy Tail are inside Tartaros's Cube headquarters, but they're too late to stop Face from being activated. The countdown is on, with less than an hour before all magic on the continent is nullified. Meanwhile, Zeref warns Natsu of a fateful choice he'll have to make?!
Franmalth uses the stolen power of Hades as he continues to battle Natsu and Lucy. Gray, Erza, and Mirajane are kept busy by other demons in the house, leaving Wendy and Carla as the only ones who can shut down Face, the weapon of mass magic destruction. Except the huge, multi-armed Ezel is waiting for them...
Wendy has powered up for her showdown with Ezel, but in the end, she and Carla may have to make the ultimate sacrifice to stop Face from going off and obliterating magic all across the continent.
While Franmalth attempts to absorb Natsu and Lucy's souls, Mirajane discovers the secret to the demons' immortality in Hell's Core, right before Seilah unleashes the restraints on her own power to take on Mira.
Jellal, Meldy, and Oracion Seis come across Rusty Rose, who tells them of his encounter with Tartaros after finding out the Dark Guild was preying on Dark sub-guilds. Later, Jellal and Meldy head off towards Tartaros, but someone doesn't want them to go...
Just when Mirajane is about to succumb to Seilah's Macro, she remembers a series of events in her childhood that could provide a clue to turning the tables on the Etherious demon. Then Mard Geer makes his move to neutralize all the Fairy Tail wizards and even scores of Tartaros soldiers on the Cube.
All of the Fairy Tail members are flash-frozen, possibly dead, within the giant Tartaros prison called Plutogrim... except for Lucy, who seems to have escaped that fate through luck alone. But that luck seems to have run out as she's pursued through the prison by the members of Tartaros, including the Nine Demon Gates! So it's a good thing she can always count on her friends, the Celestial Spirits!
Lucy is a wreck after giving up Aquarius forever in exchange for a one-time summoning of the Celestial Spirit King, who then takes on Mard Geer, the Underworld King. And Lucy finds she doesn't have time for tears as the explosive Jackal tries to take her out of the picture.
Wendy and Carla successfully dismantled Face, only to find there are thousands more! And they find out what originally turned Minerva stone cold as she confronts Erza in the ruins of Tartaros HQ.
Gray is shocked to learn that Silver is his father. Meanwhile, Natsu and the others continue their battle against the other Nine Demon Gates, while Minerva has a change of heart and Happy gets a mushroom-ectomy.
The battle between Gray and Silver continues, although it's an uphill one for the Fairy Tail members, as Silver is an Ice Devil Slayer and therefore immune to ice attacks. Meanwhile, Wendy comes up with a desperate plan to stop the 3,000 magic pulse bombs from going off in less than an hour!
Gray knows the truth, that Silver really is his father! Juvia battles Keys, the puppet master of the dead. And petite mushroom Franmalth gives the Fairy Tail members the runaround so they can't stop the 3,000 Face devices from going off.
Sting and Rogue continue their battle with Mard Geer, leader of Tartaros. Meanwhile, Erza and Minerva are still in the labyrinthine Cube, searching for the control room so they can stop the continent-wide magic pulse bomb detonation. And Torafuzar and Tempester turn into their ultimate Etherious forms to take on Dragon Slayers Natsu and Gajeel.
Gajeel is trapped in Torafuzar's toxic water. Even though his lungs are filled with air thanks to Levy, his body is quickly filling up with poison. And later, despite his body being filled with anti-magic particles, Laxus takes a last stand against the immortal Tempester.
It's Laxus's last stand against the immortal Tempester! Plus, Erza and company finally reach the control room, where the dead former Magic Council chairman is in the process of activating the 3,000 Face bombs. Kyoka and Seilah are also there, and quickly act to prevent the Fairy Tail members from interfering...
After more than seven years, out of nowhere, Fairy Tail's worst nightmare returns: Acnologia, the dragon that nearly slaughtered the guild's most powerful members. The timing couldn't be worse, as the Fairy Tail members are exhausted, but then Natsu somehow hears Igneel's voice...
Natsu interrupts the fiery battle between Igneel and Acnologia to ask his burning questions, but his former foster father gives him a task instead of answers: to steal the Book of END from Mard Geer. This prompts the leader of Tartaros to speed up Face's timeline, by having Kyoka form a living link with the activation device. Only Erza can stop her, but will she prevail against Kyoka's ultimate Etherious form?
The battle between Erza and Kyoka heats up as the demon uses her Curse power to make Erza and the other Fairy Tail members in the room ultra-sensitive to pain. And if that's not bad enough, Kyoka steals all five of Erza's senses!
Natsu, Sting, and Rogue take on Mard Geer together while Igneel and Acnologia continue their battle overhead. Meanwhile, there's still the problem of thousands of magic-decimating Face bombs set to go off, but Makarov has an ace up his sleeve...
Makarov may have a way to stop the threat of Face, but everyone's memory of it will have to be wiped afterwards. Meanwhile, the battle in the sky between Igneel and Acnologia rages on while Gray, now a Devil Slayer, joins the fight on the ground against Mard Geer.
Rogue and Sting have one last chance to take out their former, now demonically resurrected, master. Meanwhile, it's hard enough for the tag team of Natsu and Gray to make any headway against Mard Geer's ultimate form, but then the Underworld King unleashes his ultimate curse, Memento Mori!
Gray survives Mard Geer's ultimate Curse, revealing that his recent changes have left him not altogether human. Erza defeats Kyoka, but the demon has the last laugh as Face is activated. Almost immediately, the Fairy Tail members are sapped of strength as the Face units begin to siphon magic from all over the continent.
It's dragons to the rescue before the Face devices can siphon all magic from the continent. But even as one crisis is averted, there's still the final battle between Igneel and Acnologia, as well as the reappearance of another well-nigh omnipotent foe.
In this epilogue to the Tartaros saga, the dragons reveal a tragic secret to Fairy Tail, while Natsu makes a vow to Igneel's fading soul. In the aftermath, Makarov dissolves the guild, several members set out on their own quests, and Zeref drops a shocking revelation.