Sōji is an ordinary high school student with an extraordinary love for pig tails (or "twin tails"). One day a mysterious girl from another universe named Thouars appears in front of him. At the exact same time, monsters begin attacking the city where Sōji lives, declaring they will drain the world's energy in the name of the Twintails. Sōji receives a powerful armor from Thouars called "Tail Gear" which transforms him into a female Twintail warrior named Tail Red.
Senō Natsuru is your normal, everyday high school student. However, he's been chosen to be a Kämpfer, who's objective consists on fighting other Kämpfer with either guns, swords or magic. However, there's catch—first, you can't chose if you're a Kämpfer or not, and second, you must have the body of a girl to use your powers.
Ryuu Yamada is known as a delinquent in his high school; he has been bored of classes after one year of attending school. One day, he accidentally falls from a flight of stairs onto Urara Shiraishi, the ace student of the school. Yamada wakes up to find that he has swapped bodies with her! The two try to reverse the change and discover that kissing triggers the body swap. On the suggestion of student council vice-president Toranosuke Miyamura, they revive the Supernatural Studies Club. The club encounters other "witches" with different powers that are activated with a kiss!