The secret scrolls of Shinken-ryu tell of a forbidden method to unlock a fighter’s hidden spirit and grant them incredible power, albeit at the cost of their sanity. The method, known as “Yami” (闇; “darkness"), involves channelling one’s spiritual energy, or “ki” in a way that the equilibrium of yin and yang within the fighter’s spirit will be broken, allowing the dark, monstrous energy of the former to overtake the latter's natural and pure strength. Yami grants the user power above any human being, but when this power is abused, the dark energy would fully consume the fighter’s spirit, turning him or her into an unstoppable monster who only lives to fight and kill. Due to the dangers of abusing its power, for many years, the Yami method has been hidden amongst practicioners of the Shinken-ryu style. Not even the closest family members are told about it, and it was thought that the Yami method has been all but forgotten. During the climax of the second tournament, Ryuga once again reaches the final round of the tournament where he would face his brother Kabuto for the second time. The two fought a hard battle, exchanging blows one after another, and pulling off all of their absolute techniques. The battle ended with with both Ryuga and Kabuto within an inch of each other’s lives, with only one last finishing blow seperating them from victory. However, just as Ryuga was about to unleash the final blow, Kabuto, in a last-ditch effort, taps on the power of Yami, and in one fell swoop, proceeded to turn the tables and brutally beat down Ryuga, only stopping once his brother was unconscious, if not dead. Overwhelmed by Kabuto’s newfound power, Ryuga was forced to succumb to his injuries. Taking his loss against Kabuto in stride, Ryuga strived to train harder and harder in order to finally defeat the power of Yami without succumbing to the dark power himself. Around that time, a third World of Fighting tournament is announced, with a doubled prize pool from the previous tournament to attract more fighters from all around the world. However, to win the prize money is not Ryuga's goal. Instead, he joins the tournament in order to settle the score with his brother one last time.
