Gonna be the Twin-Tail!!

A typical high school student named Soji Mitsuka has an infatuation with twintail hair. When monsters show up in his town and declare that all twintails in the world are theirs, he one day meets a curious girl named Twoearle who is from a parallel universe. These creatures are fueled by human "attribute strength," or chi. Soji was given Tail Gear by Twoearle, an imaginary suit of armor powered by the twintail's strong qualities. With the armor, Soji becomes a female twintail warrior known as Tail Red, or tsuinteiruzu kankei-sha, to defend Earth.