Orochi's Fin's Assault

Orochi's Fin's Assault is an event that takes place during the Avatar arc.

Prologue
The trio of Lucy, Natsu and Happy make their way out of Crocus and head south as they begin their journey to seek out the other scattered members of Fairy Tail. Along the way, Natsu comments that he is disappointed by the lack of action after his return, challenging Lucy to a battle which Lucy decides to humour him with a short sparring match so that she can demonstrate her own improved powers. In a sudden fashion, Natsu quickly takes out a group of thieves on the outskirts of the town from their current location within it (in which he heard them), which makes him reconsider his proposal. As they stop for a rest, Lucy confesses that she is unsure of everyone's current whereabouts, but says that they should try and aim for Margaret Town, where Lamia Scale is located, as someone moved to their guild some time ago. A little later, The group arrives in Margaret Town as Lamia Scale is hosting their Thanksgiving Party parade. From a crowd outside the guildhall, Lucy and Natsu watch as Lyon, Toby and Ooba all perform for the town before Wendy and Sherria take to the stage to perform a song.

Shocked to see her now as a member of Lamia Scale, Natsu vows to rescue Wendy from "the dark side", though Lucy comments that Wendy is fine with the other guild and her friend Sherria, noting that many of the other Fairy Tail members moved to other guilds in order to find work. With the show over, Happy begins to wonder where Carla is, which on cue, a small girl with cat ears appears behind the trio and greets them, which surprises them. Concurrently, from the shadows, a group watch the Lamia Scale parade come to an end, commenting that soon they shall start their judgement on Lamia Scale with a festival of blood.

Soon after the end of Lamia Scale's X792 Thanksgiving Parade, the performers gather in a room and discuss the event. Lyon then brings Natsu, Happy and Lucy to visit Wendy, much to the young girl's joy. The three then talk about their plans to revive Fairy Tail and also about the disappearance of Makarov and the problems this is creating for the Magic Council, which has now been taken over by the Ten Wizard Saints. But, when Natsu asks Wendy to help them, Wendy refuses, saying that she is now a part of Lamia Scale. Carla, now in a human form using Transformation Magic, enters the room and supports her decision, stating that Wendy should be allowed to make her own choices. Later, in their room in an inn, Natsu and the others laze around, still shocked by Wendy's decision. Meanwhile, Wendy and Sherria talk about Natsu's proposal in their house, Wendy saying that she would never leave Sherria alone. But Sherria states that she would never hold her friend back just because she felt lonely. At that moment, a sudden explosion near the Guild grabs their attention.

Assault
Soon after, Lamia Scale Guild is bombarded, and Margaret Town is attacked by monsters summoned by Orochi's Fin. a rival guild of Lamia Scale. Natsu, Lucy and Happy arrive at the scene and rendezvous with Lyon, who explains the situation. It is revealed that this is only a small fraction of the attacking force, as the entire force is composed of at least 100,000 monsters. Ooba deduces that Orochi's Fin has a monster tamer in their ranks, so Natsu decides to join the battle to help Lamia, wanting to attack their forces from the air using Happy, alongside Wendy and Carla. Suddenly, Sherria hijacks Happy from Natsu and decides to take care of the problem alongside her Sky Slayer counterpart, leaving Natsu astonished.

Wendy and Sherria launch a counterattack upon the invading Orochi's Fin members, with their main goal to take down the summoner Mage responsible for taming the massive amounts of monsters invading the city; Wendy noting a smell belonging to a familiar figure nearby. Meanwhile, back in Margaret Town, Lucy, Lyon and Natsu are poised to defend the town and its inhabitants. Natsu, mad at Sherria for stealing Happy rushes at the invading monster army and decimates them as he moves towards the Sky Sisters' location. Lucy, at the same time summons Loke and utilizes her newfound Star Dress, entering Leo Form in order to defeat the monsters invading the town. Wendy and Sherria approach the location of the Orochi Fin's Monster Tamer, but are ultimately pinned down by the former Dark Mage of Grimoire Heart, now an affiliate of Orochi's Fin: Bluenote Stinger. As Bluenote prepares to finish off Sherria, Natsu arrives and picks her up, oblivious of the situation, yet seemingly unaffected by Bluenote's Gravity Magic.

Natsu, still mad at Sherria as he scolds her kidnapping Happy, does not realize that the enemy standing in front of him is the same man that once fought them at Tenrou Island. Bluenote seems to have some recollection of Natsu and engages him, but Natsu dodges the attack by using his flames to lift himself up. Proclaiming that Fairy Tail is not yet crushed or destroyed, Bluenote remembers the guild's name, as well as the man who defeated him, and once more engages Natsu, only to be obliterated by Natsu's roar, which became considerably more powerful, greatly surprising both Orochi's Fin members, as well as Carla and Wendy, who are baffled by the amount of power Natsu gathered through the year. After that, Natsu contiunes his tirade on burnt-clothed Sherria, but is reminded by Happy that Orochi's Fin are still on the scene, but the guild surrenders unconditionally in fear of Natsu.

Aftermath
Natsu and the group then return to Margaret Town, where they are thanked and prasied by Lamia Scale for helping them fend off the invasion. Lucy in particular wonders where Sherria and Wendy are; Yuka tells her that they are off alone together. Concurrently, on a hill, Sherria vents her frustrations to Wendy, explaining that her brash behavior during the invasion was to prove to Wendy that she didn't need Natsu, but that she only needed her and that she can fend for herself. Sherria then tells Wendy to go with Natsu to revive Fairy Tail, saying that her sibling-like feelings towards Natsu are a type of love, much to Wendy's embarrassment. Ending the conversation with the fact that they'll always be friends even if they are in different guilds, the girls hug each other in the sunset.

That morning, Wendy tearfully departs from Lamia Scale, with Toby and Ooba comically promising to carry on the "Sky Sisters" name, much to everyone's chagrin and disgust. After they leave, Lyon tries to comfort Sherria by telling her that it's okay to cry; the girl resolves not to, as she too wants to see Fairy Tail revived. Back with Natsu's group, Wendy briefly sobs at having to say goodbye to her friend, and after a brief talk-over, Lucy tells them that their next destination is Amefurashi Village: a place that is famous for its never-ending rain; and a place where a one Juvia Lockser is thought to reside.