Karinzanjutsu (火輪斬術, Fire Ring Cutting Technique) is said to be the ultimate way of killing with a sword. In the 2000 years it exists, there has only been 15 people who can be called "masters" of Karinzanjutsu. Its training has an average duration of 32 years. Gamma Akutabi is the most recent and the only known master of Karinzanjutsu, he mastered it in 4 years. All the users of Karinzanjutsu are featured by a the mark of Karinzanjutsu, a black ring with 9 lines swirling away from the ring.
Black Flames of Bloodlust
It is said that users of Karinzanjutsu are ringed by the Black Flames of Bloodlust. They can be touched, unlike regular fire and can be used as a shield or a chain.
The Black Flames can naturally be used for offensive abilities, either for destruction or reinforcing regular weapons.