Chivalry of a Failed Knight

Chivalry of a Failed Knight (落第騎士の英雄譚 キャバルリィ, Rakudai Kishi no Kyabarurii, lit. "The Heroic Tales of the Failure Knight") is a Japanese light novel series written by Riku Misora and illustrated by Won. The first volume was released on July 15, 2013. An anime adaptation aired from October 3 to December 19, 2015.

Plot
The story is set in an Alternate Earth world where humans called "Blazers" have supernatural abilities. These Blazers can materialize weapons known as "Device" which are made through a person's soul. At Hagun Academy (破軍学園 Hagun Gakuen), Blazers are selected as representatives for the Seven Star Sword Art Festival, an annual tournament event held by the seven Mage Knight Academies in Japan to determine the strongest Apprentice Knight. Hagun's performance ranking in the festival is falling and academy director Kurono Shinguji is determined to find a solution. Ikki Kurogane is the academy's F-Rank Blazer and is considered "The Worst One" for his low magical abilities, but Stella Vermillion, the princess of the European country Vermillion, is one of the top A-Rank Blazers.

On Stella's first day at Hagun, she is arranged to share a room with Ikki as a transfer student of the academy. When Ikki inadvertently discovers Stella half-dressed, he is challenged to duel where the loser has to be obedient to the winner for life. She ends up losing the duel, but they agree to become roommates. The series follows their adventures as they train to qualify as the school's representatives for the festival.