Ittou Shura

"One minute was enough. It was fine to ignore what happened afterward, but for one minute he'd become strong enough to beat anyone."

Ittou Shura (lit. Blade of Shura) is the Noble Art of Ikki Kurogane.

Description
Ittou Shura is a Noble Art of Ikki Kurogane that removes all his physical limiters, granting him tremendous power while ignoring the survival instincts of the human body. Ittou Shura, although grand, is only able to be maintained for a minute.

During his match against Tohka Todo, Ikki uses an improved version of the Ittou Shura, Ittou Rasetsu, to defeat his opponent.

Weaknesses
Ittou Shura drains the entirety of Ikki's stamina, in one minute, so he will become unable to fight, for an extended amount of time. Its usage is limited to once per day, due to the incredible strain that it places on his body. Ikki has been seen several times in the hospital after using it causing his opponents to use the "once-a-day" limit against him before in order to cripple his chances of victory.

After reaching his "Awakening" Ikki's magic power increased, so that he could even use Ittou Rasetsu after Ittou Shura. This only happened once, as Ikki is still unable to control his abilities. After training with Edelweiss, Ikki attained better control of his mana resulting in him improving his Ittou Shura, but it is unclear by how much.

Trivia

 * The Shishou martial arts technique, Kirinkou, is very similar to Ittou Shura.