Gonna be the Twin-Tail!! (2014)

Soji Mitsuka loves the twin-tail hairstyle. Following his first day of high school, he and his childhood friend Aika Tsube are enilisted by a mysterious woman named Twoearle to fight an evil force that threatens twin-tails worldwide!

Twoearle answers Soji and Aika's questions about the Tail Gear, including why Soji turns into a girl. Twoearle proposes building a secret support base under Soji's house, but to do so entails serious consequences for Soji's living condtions!

Twoearle gives the others a tour of the newly-completed secret base. When an Elemelian appears, Soji goes into action to stop the attack, but he soon finds himself in over his head. It's going to take another Tail Gear warrior to rescue him!

The Ultimaguil forces find themselves fighting an uphill battle against Twin-Tails, and Dragguildy himself decides to attack in person. Tail Red and Tail Blue step forward to stop him, but Dragguildy reveals a secret that could change everything!

The Twin-Tail Club is just about ready to start, and Twoearle gives the club's classroom her own touch. With Ultimaguil on the ropes, some new reinforcements arrive to try to turn the tide, but the Twin-Tails add a reinforcement of their own.

Erina's first outing as Tail Yellow does not go as expected, and she later confides to Soji that she may not be qualified to be one of the Twin Tails. While Soji tries to work with Erina, Aika must deal with an attack from Leviaguildy and Krakeguildy!

Twoearle recognizes Dark Grasper as being Acena, one of her own fangirls from the past. Dark Grasper takes decisive charge of the Ultimaguil invasion force and climbs her way up the pop charts as her alter-ego, the twin-tail idol Anko Iisuna.

Student council responsibilities, school work, and Twin Tails activities are taking their toll on Erina, and when her mother pushes her to straighten up, Erina pushes back. When Mikoto is unavailable, Soji must secretly escort Erina on a shopping trip.

With the realization that Anko is Dark Grasper, the Twin Tails find a hidden message in her lyrics. They decide to go to her concert to stop her from potentially holding thousands of fans hostage, but Dark Grasper has other plans in store.

Spider Guildy, a formidable Elemelian officer, arrives to deal with the Twin Tails. Their fierce confrontation ends in a draw, but a surprisingly intense attack leaves Tail Red dazed.

Soji awakens to find himself in the form of Solar Metca, a slightly more grown-up version of Tail Red. He also comes up short in combat with an Elemelian, and the others become concerned about him...

Soji feels as though his twin-tails have forsaken him, and the other girls try to cheer him up. When Arachne Guildy strikes, Aika and Erina respond, but are overwhelmed.