Oni

"I shall grind beneath my heel...all that exists."

- Super Street Fighter 4 Arcade Edition

Oni , officially named Kuruoshiki Oni (狂オシキ鬼, lit. Mad Demon), is a secret character in the Street Fighter series. Leaked images of upcoming DLC Achievements for the Xbox 360 version of Super Street Fighter IV confirm he can be fought as a secret boss in Arcade Mode, as well as being a playable character. Kuruoshiki Oni is in fact, Akuma who has lost control of his power and as well as the Satsui no Hadou, who is now an actual demon instead of a half demon, which confirms that he has transcended humanity.

Note: This character should not be mistaken as Shin Akuma, even though both have very close similarities to each other such as being a more powerful form of Akuma.

Super Street Fighter IV
Main article: Super Street Fighter IV

Oni possesses an air dash attack, the direction of which is determined by the punch button pressed. He also possesses a dashing slash which allows him to pass the opponent by, similar to his Ashura Senku. He also possesses a jumping smash attack which has been compared to Honda's Sumo Smash. It also appears that he no longer possesses his Hyakkishu attack.

Whenever Oni wins the fight, he interacts with the opponent's character, CPU or Human. He picks them up by their heads, then (offscreen) supposedly smashes their head into the ground. It is unknown whether or not he does this with every character, but it is likely. It should also be noted that this is the only character in the game that interacts with the opponent when they lose.

His Super Combo, the Raging Demon, remains intact, but now can be used in mid-air. His Ultra Combos are new and appear to be based on Super Arts from Street Fighter III: 3rd Strike.

His first Ultra Combo, Meido Gohado, is an advanced Messatsu Gou Hadou that can be fired from the air, but will not cause an animation if it is done in the air. On the ground, if the projectile connects on the first hit, the animation features Oni forcing his opponent back with the first projectile then blasting them with another, with the force of the projectile emitting energy from behind the opponent shaping into Oni's kanji character.

His second Ultra Combo, Tenchi Sokaigen, appears to be a precursor to his Kongou Kokuretsu Zan attack, where he only forms an eruption of energy in front of him, but if he hits square on the first hit, the opponent is launched up into the air, and Oni follows them up with a severely-powerful Shoryuken to the opponent's exposed back.

Trivia

 * In Japanese mythology, an Oni is a type of Ogre or Demon. This serves as a connection to both the names Gouki (Essentailly Strong Oni / Strong Demon) and Akuma (Devil). He may also be an official version of the fan based version of Akuma called Ogre Akuma, most notable as a character in MUGEN. However, Akuma states throughout the series that he is a demon, and Oni may be the subject of these particular statements, thus classifying Oni as a demon.
 * Oni may be far more powerful than Shin Akuma.
 * Oni seems to have hair that is similar to that of a Super Saiyan state and whenever his prayer beads float around him, they look like Dragon balls from the Dragonball Z (Dragonball Z Kai) series.
 * Oni's theme in SSF4 is a possible alternate remix of Akuma's theme from Street Fighter 2.
 * When battling Shin Oni, his hadoken would be fully charged whenever he fires it.
 * Oni's fighting stance resembles the artwork of Shin Akuma/Gouki from SVC: Chaos.
 * Some obvious similarities between Akuma and Oni: both wear a black gi(in Oni's case, what remains of his clothing looks like a gi's lower portion), both have red, shining eyes, both use the Shun Goku Satsu(which Akuma claims is a technique only he knows, apart from Goutetsu and other dead fighters), and, as grotesque as Oni's facial build may look, he does share some of this traits with Akuma.
 * It has been officialy confirmed by the official japanese character page for Oni(Kuruoshiki Oni) that Oni(Kuruoshiki Oni) is indeed Akuma(Gouki). The character page states that Oni(Kuruoshiki Oni) is Akuma(Gouki) transformed into a literal demon instead of a metaphorical one. How he got this way is still unknown, but It is most likely that Akuma was training as Shin Akuma and had powered up to the point that he had completely lose control of the Satsui no Hadou.
 * In Akuma's ending of Street Fighter Alpha 2, he has enough power to destroy an entire island. In Shin Akuma's ending of Capcom Fighting Evolution, he has tested his power on a comet and had completely destroyed it, this ending shows that Shin Akuma has enough power to destroy a comet third-size of Earth, In Oni's ending in Super Street Fighter 4, Oni has the power to cause a volcano to erupt by dealing a single blow to the volcano.
 * Oni's Ultra Combos are the only ones (aside from both of Akuma's Ultras) show a black and white changing background.
 * If either of his Ultra Combos is a finish, the kanji 'Ten' can be seen.
 * During the events of Street Fighter III, Akuma appears to have white hair on both sides of his head, it is most likely that he is turning back into an Oni but slowly.