A fighting style developed by Keijun (The Dark Side of the Gung-Zu Temple) taught to Lil B during his departure after the first Arc, unleashing his true inner power through anger and his quest for ultimate power.
Satsui no Hado
The Satsui no Hado is a form of chakra that is rooted in the darker aspects of the natural human instinct (including the desire to survive, trample, and impose over opposition), and on a metaphysical level, the natural occurrence and manifestation of loss, decline, and destruction. To tap into the Satsui no Hado, a person must be so consumed with the desire for winning, or else possess such intense rage, that they are willing to murder. As such, only people who push themselves to be the best at any cost can take full advantage of it, however, the untrained mind can be driven into insanity if they are not ready for it. Learning the Satsui no Hado is the first step in learning the most fatal technique known to all of their martial arts - the Shun Goku Satsu, known also as the Raging Demon.
Physical and Mental Changes:
For the people who do succeed in controlling it, they become very strong and powerful, but at the cost of losing their humanity and compassion; they develop a cold, negative outlook on life and a nihilistic detachment from themselves, as well as other people, and develop an abessive, murderous (and even suicidal) desire to fight.
Such people also gain the power to sense, and potentially influence, the emergence of the Satsui no Hado in others. Once a person has tapped into the Satsui no Hado within them, it can be very hard to resist. Keijun is the only one known to date that is able to utilize its power without completely giving in to its murderous and darkest urges.
When under the Satsui no Hado's influence, a person's eyes will glow white and red and gain sharp fangs. If one embraces it to a lesser degree, their eyes will glow blue. If one has used it to their fullest extent for too long, they will transform into a demonic being.