After studying abroad​ in order to learn fencing, Utsugi Hinata returns to his home country Japan for the first time in several years, and is greeted at the airport by a woman named Nina Clione, Ginran Academy's principal and chairwoman.

Guided by Nina, Hinata is led to a school and becomes fascinated by the scene that is being unfolded there. Sparkling sword fight​s and girls covered in beautiful armors.

"This is "Cadenza," a match between the knights."
"At this school, we teach "Chivalry.​" Hinata-kun, would you like to teach fencing here?"

To evaluate his skilled in fencing for Nina, Hinata decides to experience "Cadenza" immediately. However, instead of a gorgeous armor he thought he would be wearing, what is prepared for him are a sightly lewd bodysuit and even a wig, Hinata is made to dress up like a girl.

It is only possible at the "Theater" of Ginran Academy for the 3D armor and sword in hand to be projected virtually using cutting-edge technology.

There, he confronts a knight who is considered to be the strongest in the school, and wins.

"That girl, who on earth is she?"
"This girl is a transfer student who will be assigned as an assistant instructor starting tomorrow, a second-year student in the Knight Training Department, Unohana Hina-chan!"

Thus, Hinata, or Hina, in a place where the maidens gather, begins to live a double life​ as an instructor and a student while being dressed as a girl.

[Translated and edited from the official website]