Yōgetsu

Gonna be the Twin-Tail!! (Japanese: 俺、ツインテールになります。, Hepburn: Ore, Tsuin Tēru ni Narimasu.; lit. "I Will Become Twin-Tail"), abbreviated OreTwi (俺ツイ, Oretsui), is a Japanese light novel series written by Yume Mizusawa and illustrated by Ayumu Kasuga. Shogakukan has published 22 volumes under their Gagaga Bunko imprint since June 2012. The series follows a young male high school student with an extraordinary love for pigtails (or "twin-tails") where he encountered a mysterious girl from another universe while monsters begin attacking the city, declaring they will drain the world's energy in the name of the Twintails. He would transform him into a female Twintail warrior. An anime adaptation produced by Production IMS aired in Japan from October 9 to December 25, 2014.