Zabuza's eyes went wide and he quickly formed a series of signs with a glare. "I'll shut that copycat monkey-mouth permanently!"
A shadowy figure appeared behind Kakashi and the assassin narrowed his eyes at the figure as it formed. "What's that?!"
The form became clearer until it resembled Zabuza himself.
"Me?" Zabuza kept his eyes on the figure. "Ridiculous! Is that a Genjutsu?"
Kakashi formed a final sign, narrowing his eyes. "Water Style! Giant Vortex Jutsu!"
His Sharingan eye widened and the Tomoe inside began to spin counter-clockwise. Zabuza's eyes widened.
"W-What?!"
The water in front of Kakashi bubbled and a swirling vortex of water spun around him, growing in size until it surged forward at the assassin.
"No way!" The tsunami overtook Zabuza and flooded the area, knocking over trees as it blasted its way forward several kilometers. "I was just about to set forth that Jutsu... I can't keep up with his Jutsu!"
Sakura, Sasuke, and Tazuna raised their arms to block their faces from the raging spray of water just far enough from them to remain safe from the flood. Naruto, who was still bobbing in the water, stared wide-eyed at his Sensei's Jutsu in amazement until a series of large waves knocked him underwater and eventually deposited him onto the shore.
The surge thrust Zabuza hard against the trunk of a large tree, where he sputtered and remained fixed in place from the water's sheer pressure. Kakashi threw several Kunai into him to hold him against the tree more securely as he landed on a high branch and looked down.
"It's over..." Kakashi watched the water retreating from the shore, taking with it debris and splintered trees, having created a canyon from its blast.
Zabuza glanced up at the Jonin as he recovered his breath. "Why...? Are you able to see into the future?"
"Yeah..." Kakashi answered him under his breath and held up a Kunai. "You're going to die!"
Before Kakashi could strike, two Senbon needles were thrown from an unknown location and plunged into Zabuza's neck. Blood spurted out and the assassin was knocked to the ground suddenly, unmoving.
Kakashi's eyes widened and he followed the direction the needles had come from and his eyes rested on the mysterious masked figure in the tree across the clearing. The figure giggled quietly to itself as it looked down at Zabuza's body.
"You were right." The newcomer glanced at Kakashi from behind his mask. "He died."
Team Seven stared up cautiously at the stranger who quietly regarded them. Naruto turned to look at Zabuza, whose eyes were wide and frozen in death.
Kakashi leapt down from the branch and landed beside Zabuza and examined the fatal blow. Then, he pressed two fingers to Zabuza's neck.
"He's definitely dead." He confirmed to himself and turned to look at the masked Ninja.
The Ninja bowed slightly. "I thank you. I have been waiting for the chance to kill Zabuza."
"By the looks of that mask..." Kakashi observed. "You're a Tracker Ninja from the Village Hidden in the Mist."
The Ninja straightened and looked down at Kakashi. "Impressive. You're very knowledgeable."
"Tracker Ninja?!" Naruto glared up at the stranger suspiciously.
"You don't know what a Tracker Ninja is?" Sakura put a hand on her hip. "It's something we learned at the Academy. Tracker Ninja pursue guys like Zabuza who turn against the village they were born and raised. And when they break away from the village, Tracker Ninja go after these Rogue Ninja and assassinate them in order to avoid having the secrets of the village being leaked. That's common knowledge!"
"That's right." The Ninja glanced at Sakura. "I'm a member of the Hidden Mist's Tracking Unit whose mission it is to hunt Rogue Ninja."
"From his height and voice, he's not that different from Naruto..." Kakashi kept his eyes on the Ninja. "A Tracker Ninja...? He's not just an ordinary kid..."
Naruto ran closer to the Tracker Ninja to look up at him, looking between Zabuza's body and the Ninja with his jaw clenched tightly.
"What are you?!" Naruto balled his hands into fists and yelled up at the boy. "Hey you!"
"Don't worry, Naruto." Kakashi stood and turned to his student, sticking his hands into his pockets. "He's not an enemy."
"That's not what I'm asking!" Naruto looked at Kakashi. "I... I mean...! That guy who was so strong... He was killed so easily... by a kid who's no different from me! We're... we're pathetic! I can't accept that!"
"Well, I understand your disbelief." Kakashi stepped closer to him and rubbed the boy's head. "But... this, too, is reality. In this world, there are kids who are younger than you... and stronger than me." He glanced toward Sasuke, who gritted his teeth.
Naruto huffed and averted his eyes.
The Ninja raised an arm slightly, vanishing in a swirl of wind, and then reappeared beside Zabuza. He lifted the body and draped one of the corpse's arms around his shoulders and looked to Naruto.
"You battle is over for now. I must get rid of this corpse... because it contains many secrets. Now then... please excuse me." He raised a hand to form a sign, vanishing with the wind once more.
"H-He's disappeared!" Naruto blinked in amazement and looked around.
Kakashi lowered his headband over his left eye with a slight sigh. "He's not here anymore, Naruto."
Naruto gritted his teeth and balled his fists, sinking to his knees in the damp grass, beginning to punch the earth. "What was all this for?! What are we anyway?!"
"Naruto..." Sakura watched him strike the ground and she held one hand over her heart.
"Darn it! Darn it! Darn it! Darn it!"
Kakashi reached out to grab Naruto's arm, stopping his punches. "Things like this happen when you're a Ninja. If you're frustrated, apply it next time!" He released Naruto, whose body relaxed and he let out a short breath.
Kakashi turned back to his other students. "Our mission hasn't ended yet. We must get Mr. Tazuna home."
Tazuna began to laugh and adjust his hat. "So sorry, everyone! You all can rest at my house!"
"Okay!" Kakashi looked between his students. "Let's perk up and go!"
Kakashi turned to continue down their path, freezing in place suddenly as his eye widened, and then collapsed to the ground, suddenly unconscious.
They ran up to him, looking him over.
"W-What?" Sakura blinked quickly. "What happened?!"
"Kakashi-sensei?" Naruto bent down to look at him. Without a reply, Naruto tried to shake him. "Kakashi-sensei!"