Akuma (Gouki)
Akuma trained along with his big brother, Gouken, in the ways of Shotokan Karate underneath the teaching of Goutetsu. Both trained very hard to win the preference of their master. However, both brothers were very different in their paths. Gouken seeked the secret of the fight, the reason of why people fight, and what does fighting lead too. Akuma, by the other hand, seeked only his personal ambitions, to become powerful, and to be stronger than anyone else in the world, at any costs. Being a wise man, Goutetsu saw the fury in Akuma's eyes, and feeling a bad omen, Goutetsu decided to cast Akuma away from his dojo. Akuma was blind with anger, and vowed that one day, he would come back and teach his brother and master a lesson for daring to try to challenge him. From that day on, Akuma roamed the earth like an errand vagabound. However, he never renounced to the ways of Shotokan Karate. However, after training so many years, and mastering each and every technique of his art, Akuma couldn't believe that his training would reach an end so suddenly. He felt that there was lot more to Shotokan Karate that met the eye. He felt that Goutetsu had not teached him and Gouken the principle things of the art, since he felt empty and desiring for more. Thus, Akuma saught more information about Shotokan Karate. Upon further investigation, Akuma found a curious fact indeed: the "forbidden part", "the killing power of Shotokan Karate", and the "sealed evil". Everything merged in one main reference: the Dark Shotokan Karate. So, it was certainly true that Goutetsu had hidden this secret to them, and mostly, it was to make sure that they wouldn't be tempted by the dark side, and use the evil power to unleash something which could be fatal. However, Akuma thought of Goutetsu to be a fool to hide such important facts to him, and Gouken as well, for being an ignorant to this matter. However, it was warned tha anyone who dared tried to practice the Dark Shotokan would certainly meet a cruel death, Akuma felt he had no other choice: he had to push himself to the limits if he had to face the forces of his brother and master. Thus, Akuma began to train on the foridden ways. It caused him much pain, and was about to die in several occasions. However, for a mysterious reason, he didn't die, as if somebody wanted him to keep himself alive to unleash the power of the Dark Shotokan. Finally, Akuma learned the ultimate move of the Dark Shotokan: the Shun Goku Shatsu (Instant Hell Murder). However, in unleashing this power, Akuma sealed his own doomed fate: the dark spirits which had been sealed along with the Shun Goku Shatsu were freed as well, and all merged directly into Akuma's body. Racked with enormous pain, Akuma gained much more power, but in doing so, his body no longer was that of a human: it was now that of a demon. Little after Akuma completed this feat, he went to fulfill his promise. He arrived at Goutetsu's dojo one night. His master seemed to be expecting him, but not with so much power. Akuma laughed and said that Goutetsu was a fool in not testing the power of Dark Shotokan. Goutetsu replied that the power would only bring despair to it's user. Deaf at Goutetsu's words, Akuma went and applied the Shun Goku Shatsu anyway. A big flash of light, then nothing. Akuma saw the dead body of his master twisted and in pretty much bad shape lying on the floor. However, he knew that he wouldn't stop at that. There was still one person who had to pay: his brother, Gouken. It took Akuma a while to find Gouken. He wasn't back there in Gouetsu's dojo. He seemed to have left. Regardless, Akuma would turn the world upside down if he had too. It took him some years to find Gouken, and when he finally did, it seemed that he had lifted his own dojo and even trained several students.
However, Akuma wouldn't feel pity, not even for his brother. Thus, Gouken followed the same fate as his master: die at Akuma's hands with the Shun Goku Shatsu. However, after eliminating his brother, Akuma realized something: there were no other challenges for him in this world. He had already surpassed the power of mere mortals, and he had eliminated both his most dangerous opponents. However, in order to become the true master of Shotokan Karate, and impose his new style, Akuma had one other thing to do: kill the rest of the Shotokan disciples, in other words, Gouken's disciples. Having a new task, Akuma parted. Anyone who stood in his way would surely meet an untimely death.
Shin Akuma
This is Akuma's most powerful self, the true embodiment of everything that is evil. Basically, it's sort of "super saiya-jin" Akuma, with more speed and with far more power.