The Orochi power was devastating the world. With all the chaos and panic running amok, two clans came together to fight the menace: the Kusanagi, representing the sword that seals, and the Yagami, the shield that holds. Uniting the power of the both clans, and using the mythical crimson flames, the two bloodlines managed to seal away the Orochi power, then assigning the task to the Clan of the Yata to look over the seal. After that, both clans retired to their respective villages.

1140 years later (which means, 660 years ago), however, the bond between both clans would break dramatically. The Yagami, thirsty of the magnificent Orochi power, broke the pact between them and the Kusanagi clan, and decided to strike a deal with the Orochi: an unholy pact that would grant the Yagami tremendous power, and their crimson flames would turn into purple flames of death! The Kusanagi reclaimed that the Yagami disobeyed the pact, and they were considered as traitors. Since then, the two clans have been in a mortal war, resulting in the death of many clan members on both sides, much to the glee of the Orochi clan.

Now, in the modern ages, Kyo and Iori are out to settle the score. Although their destiny was resolved before they were ever born, Kyo and Iori seem more than willing to finish the 660 year grudge! And mostly, Iori is decided to kill Kyo at all costs, although he is destined to a horrible fate: to die before his time, victim of the ambition of his ancestors, and his cursed blood. However, Iori does not to seem to care too much about it. His heart keeps no happy feelings, and is only interested in ridding the path of enemies. However, wielding the purple flames is painful even for Iori, since the power is so great that it even hurts him!

Iori and Kyo have similiar techniques because both clans had developed together a very special martial art before they engaged in the war. That's why Iori has developed some mortal techniques, and even uses his hands as cutting weapons, his fingers tearing through the opponent's flesh. He has known to be very violent in battle, even though he hates using violence (???). His clan symbol is the crescent moon of the Yagami. His physique also allows him to be very famous among the women, but he doesn't seem to care about that, either!

Once Iori was training, he was informed about the entrance of Kyo in the King of Fighters tournament. Iori was interested and supposed he would have a perfect shot against Kyo. He then knew that a man named Billy Kane was looking for some teammates for the next tournament. Iori volunteered, and so, the trio entered the tournament. However, Iori was not interested in any of the only fighters. He only focused on Kyo. But, it seemed that he couldn't have a clean shot against him, since prior to their battle, Kyo was missing. However, Iori still felt Kyo's combat aura burning in a faraway place. When Iori arrived to the secret underground base were Kyo was fighting, he found him fighting Rugal, who was about to be destroyed by his own power. Iori felt something strange boiling in his blood while Rugal was being destroyed by the inmense power. Recognizing the power, Iori mocked Rugal, "Only those of the bloodline can control such power! You didn't have a chance!". Saying that, Iori walks away while Rugal is vanished by the huge power. Taking advantage of the power he felt in his veins, he used it to beat his teammates badly. Considering them only a bother, Iori decides he will take on Kyo next time.

By next year, Iori trained very hard, and practiced until near the border of unconsciousness. He considered himself ready to kill Kyo this time! While he was walking through a forest, Iori was confronted by two women. Iori recognized one of them as one of the secretaries of Rugal. Actually, both were the secretaries of Rugal. Iori wanted them to get out of his way, but one of them began attacking him. While he fought the women, the other told Iori that they had been watching over them, and that he would be perfect as their teammate in the next King of Fighters tournament. Iori stopped, and turned towards the other woman. Iori just smiled and released a maniacal laugh. He said he would help them if they wanted to. "But nobody touches Kyo, he's mine! Mine only!", Iori roars.

The tournament begins, and once again, considers the other fighters as trash, only thinking in his battle against Kyo. His wish comes true as his team will face the Hero Team. Kyo and Iori waited paciently until their turn to fight. Then, Kyo and Iori got their shot. It was a very dramatic battle, with flames bursting everywhere, and so much power released that it was overwhelming! However, the time ran up, and the match ended in a draw. Both fighters were exhausted, but Iori was determined to kill Kyo. Then, the host, Chizuru Kagura, interfered. She said it was useless that the two must kill each other, and instead, must be helping each other in order to erradicate the terrible power that draws nearer. Iori is enraged, and demands that she gets away. But Chizuru takes Kyo away, and disappears. Iori then shouts of madness, and begins to destroy everything around him. He would not be left without killing Kyo, and not by any smartass woman!

Iori inmediately searched out Kyo, but when he found him, he suddenly felt that feeling in his blood again. What was that feeling that made him feel so powerful, but at the same time, so painful? When those thoughts cruised Iori's mind, a very strong gush of wind blew him away. When Iori woke up, it was Kyo fighting against a very powerful man. Iori recognized the power as the same that had destroyed Rugal. So, it had to be of Orochi blood! Iori then begins to attack the man called Goenitz. He tells him that only him can take care of Kyo, and he can not interfere! Both fighters battle with all their strength, and Iori even manages to surpress his cursed blood and begin wielding crimson flames. With a final, double crimson blow, Kyo and Iori take out Goenitz, but before he dies, Goenitz tells Iori that he is doomed to serve Orochi as a servant! Iori then bids Goenitz farewell, as he disappears. Iori begins to walk away, and encounters his companions, Mature and Vice, who had let him live in order to kill Goenitz. However, Iori begins to feel extremly bad, and his blood begins to boil. His eyes get hazy, and he begins coughing blood. The Riot of Blood was in full effect! Going berserk because he can not control the Orochi power. Going crazy, Iori rips through his companions, and continues to walk away, roaring and slashing madly.

Nothing was known from Iori up to next year. He had seem to feel the Riot of Blood several times, causing several deaths. Cursing his own weakness, Iori realizes he has been entered in the next King of Fighters tournament of 1997 as a single entry. It must have been Chizuru, thinking he may help her again. Iori just laughs and, since he has no more bothers in his way, he can concentrate on killing Kyo this time! He views the spectacular display of shows and commuinications, and decides it was the perfect backdrop for Kyo's death. However, not much later, Iori once again entered the Riot of Blood yet again, and went into a killing rampage. His craziness had reached unsuspected limits, and since Orochi was involved as ever in the tournament, his power grew stronger and stronger. However, he also wasn't too much conscious of what he was doing, allowing the other fighters to submit him, and cooling him down. Iori then loses conciousness.

When Iori was sleeping, he receives a message from his ancestors, bidding him to aid Kyo in this final fight against the Orochi. This would rid the dishonor of the Yagami name, and would cleanse their own cursed bloodline. Iori woke up, and almost like if controlled by someone, he walked towards the Orochi awakening spot. He finds Kyo and Chizuru there. They are surprised to see Iori, and he just smiles, and tells them that it is ironic that after so much time of war, they should fight together. Kyo smiles as well, and both go against Orochi. They display their huge strength, as 1800 years ago, and begin to turn the tide in their favor. However, Iori gets controlled by Orochi via the Riot of Blood, but now, Iori will not be easily subdued! He takes a grasp of Orochi, and allows Kyo to punch right through them...

Nobody knows what happened after that faithful battle. However, it seems that Iori and Kyo began their last battle, to see which one prevails...

Iori awakes, surrounded by a strange place. His whole body aches, but that's the less of his worries. Kyo was nowhere to be found. He later knows that nobody knew where he had gone, but Iori knows that Kyo will not be so easily eliminated. Iori's scouting takes him to a hidden laboratory, where he believes bizarre experiments are talking place (I'm not talking Resident Evil here, OK?). To his disbelief, he finds several Kyo clones being produced! They must have taken Kyo's genetic code, and insert it into these mindless clones, obeying some twisted plot! Enraged for the tampering with his rivalry with Kyo, Iori tears the place down with an incredible display of rage and anger. The name "NESTS" is soon to pop up, and Iori vows he will find them and destroy those who dared mess up with his plans for revenge!

Not long after, Iori finds out about the King of Fighters tournament being held again. He senses that the person responsible for the Kyo clonage might be here. Iori takes a hidden role in the tournament, following the battles closely. He finally manages to catch up with the hidden NESTS base, but unfortunately for him, it is already ruined and crumbled. Iori can feel Kyo's presence, but does not see him. Iori knows that NESTS must be destroyed so he can have a fair showdown with Kyo to the very end.

After being shrouded in secrecy for awhile, Iori hears about the rumors of the NESTS cartel in action again. However, Iori does not seem too interested, but since Kyo Kusanagi was determined to stop the NESTS at any cost, Iori decides that he shouldn't let Kyo die at the hands of NESTS, but his own. Following Kyo's trace, he finally arrives at the hidden NESTS hideout in Southtown. It seems that the city was doomed for destruction by the rampant Zero Cannon, but Iori could care less how many innocent lives were lost. He dwelled deep into the base, and finally finds Kyo standing next to a fallen body. However, Iori takes things easy. He has learned to control his anger. He approaches Kyo, and like always, demands a true fight. This time, it wasn't family rivalry going on. This time, only the feeling of fighting a worthy opponent was the only thing Iori felt...and he was sure Kyo felt the same way.

The whereabouts of Iori were unknown after that tournament, and he seemed the person who less cared about what happened in Southtown. He's just unpleased that he lost his chance to kill Kyo last year. Former NESTS agent Seth actually went out to search for the miscarried youngster. Upon finding out where he was, he politely invited Iori to join his team for the next King of Fighters tournament, with a promise that he would get his shot against Kyo if he entered. Iori did not care about what his other teammates did, his purple flames of disaster only hungered for Kyo. Iori's own overwhelming aura made Seth tremble with fear. The power that Iori harnessed within him was beyond any logic! As Iori retreats with his promise to enter the King of Fighters tournament with Seth, the huge tough guy wonders what kind of surprises will Iori give them.

Iori made it clear from the beginning of the tournament that teamwork was definetly not in his plans, as he could take on whole teams by himself. His vicious attitude was even more notorious than before. Iori was indeed a threat to be considered, but as if fate would have had it, he would even have to help Kyo defeat the NESTS executives once again. This time, he had to assist Kyo's clone, K', to defeat Igniz, the CEO of NESTS, in their own space station. Once Igniz was defeated, Iori thought that since there were no longer any obstacles, he would challenge Kyo right there and now! But he was cut short when he was forced to escape from the falling space station. Iori and his teammates escaped with their lives, but Iori then realizes that his own team has considered him "expendable" by his superiors, and attempt to get rid of him before he can cause any more trouble than needed. Iori just shrugs his shoulders, and threatens that if anybody should stand against him, he would tear them down like the trash they are!

Iori is a single, self-important person who cares of nobody but himself. He considers other people to be no more than "bothers". He dislikes being controlled by Orochi, since he doesn't like to be bossed around! His only goal in life seems to kill Kyo, and won't rest until he does. He also plays music in his band in his spare time, and also manages to gather quite a number of people