
Akuma using the Shakunetsu Hadoken against Luke in Street Fighter 6.
The Shakunetsu Hadoken (灼熱波動拳 Shakunetsu Hadōken?, "Scorching Heat Surge Fist") is the name of a Special Attack and variation of Hadoken introduced in Super Street Fighter II: The New Challengers. It is used by Ryu (as well as his evil side), Ken, Akuma and Kage. It is also one of Seth's Install Arts in Street Fighter V: Champion Edition.
In Street Fighter V, Akuma's version is dubbed the Sekia Goshoha (赤鴉豪焦破 Sekia Goushouha?, "Red Crow Great Char Blast").
Origin
The original inspiration for the Shakunetsu Hadouken was a rare easter egg in the CPS1 installments of Street Fighter II, where fireballs would randomly be red rather than their usual blue color. This bewildered many players, who speculated on what causes red Hadokens to appear and if they were more powerful than regular blue ones. Capcom eventually made the red fireball official by adding in the Shakunetsu variation to Ryu's moveset in Super Street Fighter II: The New Challengers.[1]
Description
Executed by performing a half-circle forward or backward motion, depending on the character, and pressing punch, the Shakunetsu Hadoken is imbued with thermal energy that sets it on fire.
Ryu

In it's initial appearance in the Street Fighter II series, Ryu's version of the Shakunetsu Hadoken is executed by performing a half-circle forward motion and pressing Punch, causing Ryu to fire a flaming Hadoken. Ryu's version is considerably less damaging than Akuma's and only hits once, but Ryu does not charge when using it, thus making his version faster to pull off (about the speed of a regular Hadoken charge). Although it does less stun than Ryu's standard Hadoken, it can knock a foe down at close range.
In both Street Fighter Alpha: Warriors' Dreams and Street Fighter Alpha 2 (and canonically before Street Fighter Alpha 3 and the Street Fighter II series), both Ryu and Evil Ryu could only perform the Shakunetsu Hadoken via inputting a normal Hadoken motion and pressing Heavy Punch when close to the opponent. This is because the projectile only becomes the Shakunetsu version during the first 4 frames of travel time, after which it turns into a normal Hadoken as it flies onward. Apart from its knockdown capabilities, it shares the same properties as a Fierce Hadoken. It is not until Street Fighter Alpha 2 Gold where both Ryu and Evil Ryu's Shakunetsu Hadokens revert to the classical half-circle forward motion and are thus able to perform it from any range. This remained the case for Street Fighter Alpha 3 and the SNK vs. Capcom series as well, where it operates identically as it did in the Street Fighter II series (although it now deals the same amount of stun as a standard Hadoken in Street Fighter Alpha 3, and does slightly more damage and stun in the SNK vs. Capcom series).
In Street Fighter III: New Generation, the Shakunetsu Hadoken was completely absent from Ryu's kit. However, it returned in Street Fighter III: 2nd Impact with the introduction of EX Specials. In both this game and its follow up Street Fighter III: 3rd Strike, the Shakunetsu Hadoken was re-tooled to be the two-hit EX version of Ryu's Hadoken, executed by performing a quarter-circle motion and pressing two Punch buttons. This iteration of the technique has slightly faster startup and travel speed and does twice as much a damage and stun as the meterless Hadoken, along with being safe on block and knocking down at any range. It also has the unique ability to combo into itself up to four times. The Shakunetsu Hadoken operates similarly in the Street Fighter IV series and in Street Fighter × Tekken.
In Super Smash Bros. for 3DS and Wii U. Ryu can unleash a Shakunetsu Hadoken by performing a half-circle forward motion and pressing either the Attack or the Special button. It deals 1% more damage than a regular fast input Hadoken (Fast True Hadoken) and 2% more damage than a regular slow input Hadoken (Slow True Hadoken). It also does more shield damage, knocks the target back further and hits multiple times (five in total, the first four do 1% damage plus the last hit 4%). Holding the Attack or Special Button down, will increase the Shakunetsu Hadoken's speed and all of the five hits will combo into each other, whereas tapping the button will make the Shakunetsu Hadoken fly slower and the multi-hits won't combo into each other.
Ryu's Shakunetsu Hadoken functions the same way in Super Smash Bros. Ultimate, although he can now cancel specific aeiral normals into the attack.
In Project × Zone, the attack appears as the ending attack of one of Ryu's combos. In the sequel, he uses it just before Metsu Hadoken in his special move.
Akuma

In his initial appearance in Super Street Fighter II Turbo, Akuma's Shakunetsu Hadoken is executed by performing a half-circle forward motion and pressing Punch. Unlike Ryu's version, Akuma glows red and charges slightly before releasing it. The Light Punch version hits one time and recovers the fastest, the Medium Punch version hits twice, and the Heavy Punch version hits three times. The latter two versions both have higher recovery than most other projectiles. Another major difference from Ryu's version is that Akuma's Shakunetsu Hadoken knocks the opponent down regardless of the range.
From the Street Fighter Alpha series onwards, Akuma's Shakunetsu Hadoken is executed by performing half-circle backward motion and pressing Punch.
The EX version introduced in Street Fighter IV hits three times, recovers as fast as the Light Punch version, and does more damage.
In Tekken 7: Fated Retribution, Akuma has three versions of this technique: Light (executed by pressing Left Punch), Heavy (executed by pressing Right Punch), and EX (executed by pressing both Punch buttons). The Light version does 1 hit and leaves the opponent standing, has faster startup and travels slowly. The Heavy version travels faster, hits three times and knocks the opponent down. The EX version travels the fastest, hits three times, does the most damage, knocks the opponent down, and has the same amount of startup as the Light version.
In Street Fighter V, Akuma's Shakunetsu Hadoken, now called the Sekia Goshoha, has a new charging animation, with Akuma now channeling thermal energy into each of his hands while charging. The EX version also deals steady damage in the form of grey health to enemies near him during the move's startup (similar to Dhalsim's first V-Trigger). Should the projectile land, however, it still does the normal damage, removing the grey health with it.
In Street Fighter 6, the Shakunetsu Hadoken is now the fully charged version of Akuma's Gou Hadoken. Executed by performing a quarter-circle forward motion and holding any Punch button for at least 49 frames (or holding the Special button for 49 frames for Modern control), Akuma poses with his arms outstretched, channels thermal energy into each of his hands, cups them together, and launches the fireball at his opponent. The Shakunetsu Hadoken appears larger and comprised of a black and gold magma-like substance that explodes on contact. Compared to previous games, Akuma's Shakunetsu Hadoken has much longer startup. The only difference between the meterless version of this move is the projectile travel speed, with the Light Punch version travelling the slowest and the Heavy Punch version travelling the fastest. All three versions deal 3 hits of extremely high damage that knocks the opponent down. The OD version has much faster startup and deals three hits of even higher damage.
Akuma does not have this move in the Marvel vs. Capcom series. In the Street Fighter IV series, the alternate form of Akuma known as Oni has the Gorai Hadoken, a projectile imbued with electricity instead of thermal energy; its gameplay purpose remains largely the same as Akuma's Shakunetsu Hadoken.
Evil Ryu

Evil Ryu's Shakunetsu Hadoken in Super Street Fighter IV: Arcade Edition.
In the Street Fighter Alpha and SNK vs. Capcom series, Evil Ryu's Shakunetsu Hadoken is executed by performing a half-circle forward motion and pressing Punch, and is functionally similar to Ryu's: he does not charge when using it, and only hits 1 time.
When Evil Ryu returns in Super Street Fighter IV: Arcade Edition, his Shakunetsu Hadoken is instead executed by performing half-circle backward motion and pressing Punch. It functions largely the same as Akuma's Shakunetsu Hadoken, including the EX Special version, in that Evil Ryu charges when using it and it hits 1-3 times.
Ken

In Street Fighter V, Ryu has no access to the Shakunetsu Hadoken, with it instead being found in Ken's arsenal. Activating his V-Trigger, Heat Rush changes all of his regular Hadokens into the fiery Shakunetsu Hadoken. This move causes a knockdown irrespective of the distance it hits at. The meterless versions deal one hit, while the EX version hits twice.
Kage

Kage's Shakunetsu Hadoken in Street Fighter V: Arcade Edition.
Kage's fireball shares similar properties to Akuma's Sekia Goshoha. He charges slightly and glows red prior to releasing the projectile. The fireball hits 1-3 times, depending on the strength of the punch button pressed. If two punch buttons are pressed, then the EX version is performed, hitting the opponent four times. Shankunestsu Hadoken is the only projectile in Kage's arsenal that travels fullscreen (with the exception of Airborne Hadoken.) It can extend combos in the corner, thanks to its multi-hitting properties.
Seth

In Street Fighter V: Champion Edition, Seth gains access to the Sekia Goshoha after landing a successful Tanden Install on Akuma. Executed by pressing Medium Punch and Medium Kick simultaneously, Seth glows yellow, charges briefly and releases a flaming fireball.
Seth's version of Sekia Goshoha operates identically to Akuma's Heavy Punch version, travelling quickly, dealing three hits to the opponent and knocking them down, while also having relatively slow startup and recovery. While Seth's first V-Trigger, Tanden Ignition, is active, he can cancel Sekia Goshoha into Titanomachy by pressing Heavy Punch and Heavy Kick simultaneously after the projectile collides with the opponent.
Tactics
Prior to Street Fighter IV, Akuma and Evil Ryu's versions could be nullified by another single-hit projectile, limiting the move's usefulness to 'chipping' an opponent on wake-up or forcing them to parry it (thrice) in the same scenario (Street Fighter III only). However, in the Street Fighter IV series, every hit of a projectile counts, allowing the heavy punch version to beat out regular and EX projectiles and still hit. Though this gives Akuma an option to win 'projectile wars' without using any meter, it requires him to preempt the opponent's moves, and is more often used for its chip damage.
In Street Fighter V, Ken's version causes a knockdown on hit without costing Critical Gauge like Ryu's nor needing to 'charge' like Akuma's; thus combining the best properties of Ryu's and Akuma's versions. This is obviously offset by the inherent time limit on his V-Trigger. The knockdown effect of this move helps immensely in maintaining Ken's already excellent offensive pressure while his V-Trigger is active.
In Street Fighter 6, Akuma's Shakunetsu Hadokens are great for fireball wars, as its three hits allow it to overpower any other non-Super Art meterless projectile. Due to Street Fighter 6 a having projectile priority system where OD projectiles overpower meterless projectiles without removing any hits, Akuma must be aware of his opponent's own projectile when firing.
However, this issue is mitigated by the OD version of Shakunetsu Hadoken, which deals three hits while also having the priority of an OD projectile. OD Shakunetsu Hadoken has among the highest priority of any non-Super Art projectile in the game, beating out all projectiles besides Ryu's OD Raiko Hadoken and Luke's Fatal Shot, which it clashes with, and Guile's 3-bar OD Sonic Cross, which it loses to (although the Sonic Cross loses 3 of its 4 hits in the clash).
In the Super Smash Bros. series, Ryu's Shakunetsu Hadoken varies in utility based on the version used. Slow Shakunetsu Hadokens are great for spacing near opponents and setting a set up against floaty characters (2*light Down-Tilt into strong Down-Tilt cancelled into a Slow Shakunetsu Hadoken).
In contrast, the Fast Shakunetsu Hadoken is great for spacing far opponents and will true combo all non-floaty characters (2*light Down-Tilt into strong Down-Tilt cancelled into Fast Shakunetsu Hadoken). The multi-hits allow Ryu to set up pressure and possible following setups in a match. But it also has a downside to it too. Since the player has to do a longer motion than for the True Hadoken, they need more time to pull the motion off.
Gallery
Sprites
Ryu
Akuma
Shin Akuma
Screenshots
Gif Animations
Ryu
Akuma
Evil Ryu/Kage
Ken
Seth
Trivia

Kirby firing a Shakunetsu Hadoken.
- Originally, Shakunetsu Hadoken for both Ryu and Akuma was meant to be included in the gameplay of Marvel vs. Capcom 3: Fate of Two Worlds, but it was dropped and the sound files were left unused.[citation needed]
- In Super Smash Bros. for Nintendo 3DS/Wii U, Kirby can gain the Shakunetsu Hadoken along with the normal Hadoken after copying Ryu.
- Street Fighter V is the first game in the series where the Shakunetsu Hadoken has a different appearance depending on the user. For instance, Ken's fireball and collosiion flame effects are much brighter than the that of Satsui no Hado users such as Akuma, Kage, and Seth, who's instead use a much darker shade of orange mixed with black.