俺、ツインテールになります。

Souji Mitsuka is a high schooler with an outsized devotion to twintails. When the Ultimegil invaders begin draining Earth of the 'attribute' energy they feed on, Twoearle, a girl from a parallel world, hands him the gear that turns him into Tail Red, a twin-tailed warrior. Souji takes up the fight against the monstrous Elemelion, joined by fellow twin-tailed fighters Aika Tsube and Erina Shindou.