A filler arc that takes place after the Seven Years Arc
. A mysterious girl name Michelle suddenly comes looking for Lucy, delivering a clock key as her inheritance from her father. However a militia like church is likewise after the key and the clock pieces of which it unlocks. Forcing the Fairy Tail members to search for the pieces before they do and try to stop their plan.
Key of the Starry Sky Arc
has the following tropes:
- Back from the Dead: Klodoa, who was crushed by Zero in the Oracion Seis Arc.
- Blob Monster: Sugarboy's power which summons blob monster that sap one's strength.
- Broken Aesop: Erza spends a lot of time trying to shove down Cobra's throat that The Power of Friendship is better than power gained through sacrifice... and then beats him only because he got distracted when he heard his friend Cubelios/Kinana coming.
- Church of Happyology: The Zentopia Church
- Gotta Collect Them All: The clock parts.
- Distaff Counterpart: Mary Hughes to her Edolas counterpart, and Dan who fills in for Erza Knightwalker.
- Fusion Dance: Mary does this in the climax of her fight against the Strauss siblings by stealing and later merging with Mirajane's Satan Soul form.
- God-Created Canon Foreigner: Despite the anime-only status, the arc is actually considered canon in the main story as it's mentioned during the Grand Magic Games arc.
- Heel-Face Turn: Earthland Coco. In fact, it pretty similar to her Edolas counterpart as both befriend Lucy and switch sides after questioning their group's motives.
- Męlée ŕ Trois: Between Fairy Tail, the Legion Corps, and later Oración Seis
- Nice Job Breaking It, Hero: Fairy Tail manage to collect all the clock parts. But in doing so they gather them all in one place for the Oración Seis to take from them later and activate the doomsday device. They also find out later that they were just supposed to protect the clock part Lucy's father sent, not collect the pieces.
- Oh Crap: Mary Hughes when Mirajane switches to her Satan Soul: Halphas form and trashes her completely despite having taken control of Mirajane's first Satan Soul form.
- People Puppets: Mary Hughes power, which, unlike her Edolas counterpart, can actually control people.
- Poor Communication Kills: If the Zentopia church had bothered to tell Fairy Tail what the clock pieces were for in the first place rather then attacking them, none of this would've happened.
- Unexpected Inheritance: The clock hand Lucy's father leaves to her.
- Wham Episode: Gildarts and Laki manage to infiltrate one of the Zentopia's churches and defeat the inhuman church members inside. However, as they go further inside they find a woman in a comatose state being kept alive by a magical machine. Reading her charts they find that she's Michelle Lobster. The following episode reveals that the Michelle who was traveling with Lucy's group is indeed a spy, the true sixth member of the Oración Seis, who calls herself Imitatia.