Enter Zabuza

"Well well well. Look what we have here.", Said a man who had landed atop the sword.
"Zabuza Momochi" Kakashi Darkly sated
"A-rank criminal from Kirigakure. One of the former 7 swordsmen of the mist." Naruto said adding upon Kakashi's words.
"Well, it seems that Konoha has started to produce some decent genin, Kakashi of the Sharingan.".
Sasuke and Shikamaru's eyes widened considerably at hearing this.
'What!? A Sharingan?' Sasuke thought in disbelief
'Sharingan is only awakened in the Uchiha clan and as far as I know, Kakashi-sensei is not an Uchiha.'
Naruto meanwhile was only smirking at his teammates.

Flashback
Office of the 3rd Hokage

"Naruto, I need to tell you something about Kakashi," The 3rd began
"I already know about his Sharingan, I sensed it earlier but what I am wondering is how he got it?"
"I figured that you would want to know how this happened. Well, sit down for a long story. It all started in the 3rd shinobi world war. Kakashi was on a team with Obito Uchiha and Rin Nohora with your father, the 4th Hokage, Minato Namikaze. The 4 of them had a Mission in Kusagakure. During the Mission, Rin got captured. Kakashi wanted to leave her and finish the mission because his father committed suicide because after saving his comrades but failing the mission he was shunned by the same comrades. But getting back on point Kakashi wanted to leave Rin to the Kumo shinobi. But then Obito left on his to go and save Rin. He then had an encounter with 2 Kumo Jonin and was about to die but Kakashi appeared and Saved him. They both fought the Kumo nin but halfway through the battle, Kakashi lost his eye to some Kumo nin who could make himself invisible. The Jonin was about to stab Obito but he surprised everyone and instead stabbed the Jonin. This happened because he awakened his Sharingan and was able to see the chakra pathways of the Kumo nin. They then rescued Rin but on the way out a few boulders fell and Kakashi was about to crush by one but Obito pushed Kakashi out and took the boulder. As he was dying he asked Rin to transplant his left Sharingan to Kakashi's left eye because that was the eye he lost. Just as more Kumo shinobi were arriving your father appeared and teleported Rin and Kakashi out. Sometime later during the war, Kakashi was about to kill an enemy Ninja when Rin jumped in front of his Chidori which he was able to perfect because of the Sharingan giving the eye to be able to see at such extreme speeds. Rin said that she needed him to kill her because during the time when she was kidnapped the Kumo Jonin sealed the 3 tails - Isobu within her so that it would be uncontrollable and go on a rampage within Konoha and one of Konoha's medics would lose their Chakra system. Kakashi was never the same after that. He fell into a depression and joined the ANBU Black Ops. (暗殺戦術特殊部隊 Romaji: Ansatsu Senjutsu Tokushu Butai)."

Present time

"Hand over the old man and I won't have to Kill you Kakashi," Zabazua said
"Can't do that Zabuza. He's our client." Kakashi replied
"Fine then, We'll do it your way. Ushi-Mi-Hitsuji, Kirigakure no Jutsu"
A thick mist starts to envelop the area using the existing water and making it into the mist.
"I'll take care of this," Naruto says completely unaffected by the killing intent," Ushi-Inu-U-Mi Futon: Daitoppa" The mist starts to dissipate from the area.
"Oh, this boy seems to be skilled in ninjutsu. Not bad for a genin." Zabuza says impressed," Alrighty then let's step it up"
"Tori! Suiton: Suiryuudan no Jutsu" Kakashi and Zabuza say at the same time
"Suiton: Daibakufu no Jutu" Kakashi said immediately after
Zabuza gets hit by a vortex of water and is washed away

Suddenly A ninja with an Anbu mask appears and throws Senbon needles at Zabuza.
The mysterious person says "Thank you. I have been hunting Zabuza for a very long time.
With that the mysterious

"Alright then Guys, Let's get to Tazuna's House." Kakashi says before promptly collapsing