Key of the Starry Sky arc

The  is an anime-only arc of the Fairy Tail series. This arc takes place during the X791 arc.

The Beauty, the Beast and the Ball
Natsu Dragneel, Lucy Heartfilia and Happy decide to go on a mission and pick one from the request board at the Fairy Tail Guild. The client's name is Count Balsamico and Macao comments that they host a Magic Dance Ball; a dance for magicians only. Natsu wants to go, but Lucy tells him that he needs to know how to dance first. Outside, Lucy tries to teach Natsu how to dance, but he steps on her feet. Meanwhile Mirajane explains Romeo what is social dance. Then Gray shows up and tries to dance with Lucy, but gets kicked by her. Erza shows up and states that she was known as the 'Dancing Demon', but she basically spins her partner like a top. Then, Lisanna also tries to teach Natsu to dance and spins him like a top, like Erza. Elfman shows up,and Erza grabs him and spins him like a top, and soon enough, other guild member such as Warren, Wendy, Happy, Carla, Levy, Gajeel and others start to dance outside the guild.

Natsu, Lucy, Gray, Erza, Elfman, Wendy, Warren, Happy, and Carla all end up going to the Magic Dance Ball. Once there, they are greeted by the client's daughter, Aceto. Inside, the count tells them that the ball is to pick Aceto's future husband. He tells them that the family heirloom is a ring, and he only brings it out once every seven years at the Magic Dance Ball to choose Aceto's husband. He suspects that Velveno wants to steal the ring, and tells them that Velveno uses Transformation Magic and Magical Drain, which allows him to copy the magic of any opponent.

Wendy, Lucy, and Erza get ready for the ball, and Wendy notes that she should cast Troia on Natsu, since the dancers dance on floating, moving platforms. Gray, Natsu, and Elfman are inside, while Warren, Happy, and Carla are outside, watching the scene from communication lacrima that Warren had previously set up. They are all communicating with Warren's telepathy. A man asks Erza to dance, and Warren thinks he might be suspicious. Natsu and Gray start towards him, but when Erza starts spinning him, everyone realizes she is fine by herself. Next, a man asks Lucy to dance, and he is also suspect. Natsu and Gray, however, are grabbed by two women who want to dance. A woman asks Elfman for a dance, and everyone suspects her because no one in their right mind would ask Elfman for a dance.

Natsu and Gray go after him but are interrupted by two ugly ladies. They get rid of their partners and start towards Elfman, and manage to have Gray switch places with him. He asks what kind of magic she uses, and the two start to have an ice magic fight.

Soon, Aceto comes down, and at midnight, the Balsamico ring is revealed. The count declares that whoever gets that ring is worthy of becoming Aceto's husband.

Later, a young boy asks Wendy for a dance, and then Happy, Carla, and Warren discover that the real boy has been tied up by a man with an afro. Warren immediately warns Wendy that she is actually dancing with Velveno and she gets away from him. He cancels his transformation magic and uses Sky Dragon's Roar to steal the ring. Natsu starts fighting with him, but is ineffective since Velveno already copied his Fire Dragon Slayer magic. Erza tries to use her Purgatory armor, but is also ineffective.

Velveno states that he has copied every member of Fairy Tail's magic but that he isn't there to fight them. He then holds the ring up to Aceto and asks her to marry him. They were friends growing up, but her father forbade him from seeing her anymore, so he started doing crime. While he was in prison, he never stopped thinking about her, so he broke out of prison and tried to get to her seven years ago, as well. Everyone is shocked when Aceto accepts the proposal, including her furious father.

However, she says that he must pay for his crimes first. So, the guards come and take him away, but they promise to see each other again. Lucy wishes that she could be proposed to like that, and then is approached by Natsu. However, he only came to tell her that he ate too much and is going home. She responds by asking him to stay with her for a little while longer, and they begins to dance. The moment is ruined, when Natsu states that Wendy's Troia ran out and Lucy can be heard screaming to be let down from the platform.

Trivia
Natsu, Lucy, Gray, Erza and Wendy's clothes are similar to film's clothes