Saito knew that his opponent was on another level from the enemies he met during his missions. He looked at Sasuke and Sakura.
Saito: "Sasuke use your Sharingan to break the Genjutsu, then take Sakura and Naruto out of here."
After barking his orders to Sasuke he used his full speed to attack Orochimaru.
Orochimaru was surprised he could only see a flash. Before he was lunched back further away from his primary goal. Using his snake like body movements he managed to reduce the damage and also stop himself from been dragged further away from his pray.
Saito was surprised by Orochimaru's movement he knew that he would need to raise his power to the limit to at least be able to hurt him.
Orochimaru while standing on a tree summoned a giant snake, wich directly lunged at Saito. Saito jumped up avoiding the lunging attack and using a tree branch, he used it to lunch himself like a missile towards the head of the snake.
The attack was effective as it knocked the snake out, but Saito could feel the bones in his leg crack, the pain was immense but he soon started to heal the power up of his ability started to show its effects. Orochimaru didn't lose this opportunity and started heading towards Sasuke's direction. Luckily Saito could catch up, Orochimaru turned his head and made hand signs. The next scene was truly horrifying. From Orochimaru's mouth a sword was lunched directly at him, the sword was held by Orochimaru's tongue, wich was about two meters long. He was in midair and could not use any jutsus. Using every brain cell he had he took a kunai with a steel wire he lunched it towards a tree and used the wire to avoid the attack, after missing his target the sword was retracted inside Orochimaru's body. Saito shuddered at this disgusting display but he still had to stop his advance.
Saito took a bunch of Kunais and lunched them past Orochimaru. The later felt a sense of danger and directly stopped his advance and summoned a snake to shield him. And he was right the Kunais had explosive tags on them and directly detonated in a raging explosion. The snake was cooked alive.
Saito took this opportunity to jump towards Orochimaru in order to hold him. What followed was a crazy exchange of attacks that would have made any Genin and Chunin watching to shudder. Saito's attacks had a great destructive powers and Orochimaru wasn't a sanin for nothing, he would have crippled Saito without effort if not for Saito's surprise attack. That first attack actually managed to hurt him enough to hinder him in combat he could barely see, but if he manages to heal himself he will turn the situation around.
Saito also didn't stop his assault putting everything he had into his attacks and was reaching his limit. Orochimaru's attacks consisted of waves after waves of venomous serpents and to top it off Orochimaru himself moved like a snake. Saito's body didn't have any wounds on it due to the chakra mode, but the continuous use put a huge strain on him. And for the moment he could only endure while stopping Orochimaru from using any jutsus. Orochimaru's speed in making signs was lightning fast and if Saito gives him a single moment of relief he would turn the situation using his jutsus.
Saito finally could no longer hold on, and in a last ditch of effort he accelerate his blood flow further his regeneration was barely keeping up with the damage and the pain became excruciating but Saito knew that this wasn't the time for complaint. Ignoring his body's screams of pain he lunched a kick with all his weight behind it. Ignoring the attacking snakes. Orochimaru was taken by surprise at the explosive increase of speed and power and was hit right in the abdomen. If it was another ninja he would have died with all his internal organs turning into mush. But Orochimaru managed to lessen the damage using his body's flexibility allowing himself to be lunched by the attack. After a bit he stabilized himself and at the corner of his mouth a string of blood could be seen. After this attack Saito blacked out his body and brain could no longer handle the stress. Saito laid motionless on the ground.
Orochimaru didn't lose his time and directly healed his body, like a snake he discarded the damaged body. And from his mouth came out another undamaged Orochimaru leaving behind a dead empty husk.
Orochimaru: "That was really interesting. I should collect him. He would make an interesting test subject."
Just as Orochimaru started walking towards Saito. He heard a whistling sound and directly jumped from his place. The place he was standing at was riddled with Kunais and shurikens. A few ninjas appeared from the forest, they weren't candidates and were wearing animal masks.
Orochimaru: "The Anbu, how troublesome."
Just as they tried to catch him he disappeared in a cloud of white smoke.
The two newcomers, went directly to Saito checking his pulse. After verifying his body for any signs they took him and moved him in the direction of the village. The forest was silent and the only evidence that an intense battle took place was the destroyed trees.
=Hokage's Office=
An Anbu was kneeling in front of the Hokage and besides him was Anko.
Hokage: "So Orochimaru managed to sneak his way to the Chunin exam. His target is most likely Uchiha Sasuke, Anko you should stay I need to help seal the cursed mark."
Anko nodded in acknowledgement. The hokage sent an elite Anbu team directly after being informed about this. He also received another rapport from the proctors of the second exam apparently, one of the candidates felt an ominous chakra and sent his friends to inform the proctors while he went to check the disturbance.
Just as he was about to dismiss the Anbu, the team he sent came back.
Anbu1: "Reporting! Orochimaru managed to escape but he didn't manage to catch Uchiha Sasuke, The kyuubi jinshuriki is also safe. We found a Konoha Genin battling Orochimaru, the moment we arrived he had lost consciousness, his body was damaged, he suffered from muscle fatigue and many bone fractures. He apparently helped the members of team 7 escape from Orochimaru."
The Hokage was surprised, he didn't know of any Genin who could hold on his own against a Sanin.
Hokage: "Who is this Genin?"
Anbu2: "According to our records his name is Saito Nakamura, member of team 4, led by Yamato. He showed great interest in medical Ninjutsu and could be seen training almost daily. He was investigated two years ago for his sudden contact with the kyuubi Jinchuriki."
The Hokage suddenly remembered that incident. The investigation was closed as he was not deemed a treat.
Hokage: "Any information on how he managed to hold back Orochimaru?"
The Anbu started talking about the information gathered by them concerning his entourage, his training and also the jutsus he created.
Hokage: "Make sure that he is ready for the 3rd part of the Chunin exam. Tell the medical nins of the hospital to take care of him. Also keep an eye on team 7."
After saluting the Anbus disappeared from the room.
The Hokage turned towards Anko.
Hokage: "Anko prepare for the sealing of the cursed seal."
Anko nodded. She could only think about how unbelievable that Orochimaru was stopped by a Genin.
Anko suddenly realized, that name she knew who the genin was. She remembered a black haired kid with Hazel colored eyes. He didn't look impressive at first but he was quite polite so she didn't hate him.
=Konoha Hospital=
In a room, laying on a bed Saito finally opened his eyes. After a few seconds he finally remembered what happened.
Saito: "Damn it! I almost killed myself."
Saito started to remember his battle. And once again he learned that he was still far from being able to protect himself in this world. The only reason he was alive is because of the help of the ninjas that arrived at the last second.
He hoped that Naruto and his teammates managed to finish the test. He looked out of the window it was dark.
Saito started using the Mystical palm technique to heal his body. And after he exhausted his own chakra he fell asleep. He was glad to be alive.