The Power of Nothingness is a state of consciousness transcending ordinary perspective, born through spiritual and mental refinement. Bearing common traits with states of being within Buddhism and martial arts, it is the power to act without being attached to emotions and thought, free of fear, anger, and ego, to draw upon the contents of one's heart intuitively without obstacle and hesitation, and to be aware of the world and to know one's place and meaning within its vastness, to flow with all of creation without the need of worry, desire, and doubt.
It is the complete opposite of the Satsui no Hado. As such, it can only be used by a person of pure mind, compassion, mercy and peace. Such a person must have embraced the peaceful and spiritual aspect of the art to their fullest extent. Just like the Satsui no Hado, it makes a person unbelievably powerful, granting invincibility (spiritually and physically) to many attacks, as well as sealing off evil power and making the user a stronger fighter.
Gouken has practiced with this power throughout his years of training with Goutetsu, and after he had completed his training and left his master to begin his own dojo. He is the only one who has used this power in battle in the games, as shown by his 'Shin' form. Ryu and Ken have awakened this power, as shown below, but have not mastered it to the same extent.
Near the beginning of the animated movie Street Fighter IV: The Ties That Bind, Ryu said to himself that he sought a power better than the Satsui no Hado, but has no clue what it is, all the while arguing with Akuma's voice in his mind.
Later, when Crimson Viper refused to tell Ken where his wife was and attacked him with an electric fist - that had sent Ryu reeling even while blocking it - Ken awakened the Power of Nothingness, repulsing C. Viper with a single block while keeping a resolute and justice toned face. C. Viper retreated and reported back to the CIA; her undercover identity as S.I.N. agent 'Maya' was useless now that Ken could defeat her easily. C. Viper noted to Ken before she left that while Ryu using the Satsui no Hado was impressive, Ken was "no slouch" with the new power he showed, relatively. Ken realizes after reuniting with his wife that he has a power that comes from protecting the ones he loves, and that he would never need the Satsui no Hado, even if he had the talent for using it.
Near the movie's climax, Seth was trying to force Ryu to use the Satsui no Hado. Seth questions why Ryu, a man who seeks power, keeps the Satsui no Hado's power locked inside - as he described it, power was the natural human inclination to trample on others and the natural destruction of human life. When almost beaten, Ryu finally realizes what the power he seeks really is, which is the natural 'destination' of human life, and the courage to stand up against evil and win. When Seth laughs and argues that power is power and that there is no difference, Ryu shows him the difference and awakens the Power of Nothingness, stopping Seth's near-invincible punch with one grab.
At first, his power goes off the charts when analyzed, just as with the Satsui no Hado, but then the readings show an infinite amount of zeroes, symbolizing invincible nothingness. The skin on Seth's arm where Ryu grabbed it starts burning away; as Seth charges at Ryu in fury and shock, Ryu summons all his power and fires a purified Metsu Hadoken at Seth that blasts 50 feet away, leaving his body completely battered from the impact and causing him to go into a series of muscle spasms, which leave him nearly completely helpless after they subside. Ryu is then shown standing on the stage with his arms out, falling flat shortly afterwards. As Ken and Sakura surrounds Ryu, Ryu looks at Ken and states that he could feel the Power of Nothingness within him as well.
- See also: Hado Kakusei
In Ultimate Marvel vs. Capcom 3, Ryu has access to a powered up mode called Hado Kakusei (波動・覚醒 Hadou Kakusei?, "Surge Awakening") which is reminiscent of the Power of Nothingness; it envelops him in a blue aura and turns his eyes a pure white. Ryu suffers minor damage over time while in this mode, but even though it's an install Hyper, he is still allowed meter gain. His level 1 Hyper Combos are granted increased damage while his speed and overall combo potential are also increased. His Shin Hadoken has the ability to reflect off of surfaces though it cannot aimed up or down like his Shinku Hadoken, but because it also hits above and behind when standing or behind and below when in the air, it is difficult to evade. Compared to the Shinku Tatsumaki Senpukyaku, the Shin Tatsumaki Senpukyaku has a dramatically increased, pillar like vertical hit box hurricane that seems to generate a storm.
The Power of Nothingness is one of the central concepts to Street Fighter: Assassin's Fist. Having seen what the Satsui no Hado did to his brother and believing that there must be another way to tap into the ki needed for Ansatsuken, Gouken travels the world. Years later, he explains to his students that during his travels a kung fu master named Gen set him on the path to unlocking the Power of Nothingness, and it is this power that Gouken teaches them to tap into for their arts, completely altering the school's tradition. Emptying oneself of everything takes extreme discipline however and they express disbelief that it can be done instantaneously in the middle of battle. Ryu mentions that his ki in this state feels cool, while Ken says that his feels hot. In early training, Mu no Ken seems to be stimulated by following by a particular meditative kata, which presents more difficulty and less speed of progress than following another kata which stimulates the Satsui no Hado, but is "purer."
- While not named or stated, a similar power was displayed by Ken in the US cartoon, when he taps into it to defeat Akuma.
- The idea that Gen showed the path to this power to Gouken as proposed by Street Fighter: Assassin's Fist would explain how both were able to survive Akuma's Shun Goku Satsu; the game's storyline explains that both were able to "empty their soul" in time.