The "school sword action" story revolves around Magic Knights, modern magic-users who fight with weapons converted from their souls. Ikki Kurogane goes to a school for these Magic Knights, but he is the "Failed Knight" or "Worst One" who is failing because he has no magical skills. However, one day, he is challenged to a duel by Stella, a foreign princess and the "Number One" student. In this duel, "the loser must be obedient for life".
E1
Ikki Kurogane walks in on Princess Stella Vermillion changing clothes. A duel will settle the matter, but Stella raises the stakes, obligating the loser to lifelong servitude.
E2
Ikki's sister, Shizuku, enrolls in the school and causes quite the commotion upon seeing him. With Shizuku's arrival, Stella learns more about Ikki's history.
E3
Shizuku invites Ikki to go shopping, but is annoyed when Stella joins them. Ikki meets Shizuku's roommate, whose device helps the group as they encounter some serious trouble!
E4
Ikki's first official match approaches! Unfortunately, he and his opponent, Shizuya Kirihara, have a history. Worse, Kirihara has the immediate upper hand due to his device.
E5
As a result of his selection match performances, Ikki gains an unexpected following. Kagami gives Stella some advice that may save the princess and Ikki from parting ways.
E6
Another student wishes to be Ikki's pupil, but doesn't quite know how to ask. Despite her initial awkwardness, Ayatsuji proves to be a hard worker and talented with a sword.
E7
Ikki's impending opponent might be the most difficult one yet. He'll have to rely on his skill and determination to help a friend rediscover their honor.
E8
In an effort to help Ayase and her father, Ikki challenges Kuraudo Kurashiki, a swordsman from Donro Academy with the nickname "Sword Eater".
E9
Stella and Ikki head to what they think is a vacation, only to find multiple surprises lying in wait. Meanwhile, Shizuku makes a visit home.
E10
Shizuku's next opponent is none other than the student council president, Toka Todo. In the clash between lightning and water, which blazer will emerge as the victor?
E11
An innocent kiss shared in secret becomes the catalyst for a scandal, and Ikki is taken by the ethics committee on counts of "indecent" behavior with the Crimson Princess.
E12
The stage is set and stakes run high as Ikki prepares to face the unbeatable Raikiri. In the end, who will be the victor?