Back at the training ground, Naruto, Sasuke, and Sakura stared at Kakashi. For a moment, none of them spoke.
Sakura lowered the fist she had raised to attack him.
"Kakashi-sensei... how did you escape?"
She had been watching him closely, but she had not seen him move. Even the Body Flicker Technique would leave some trace, yet Kakashi had simply vanished.
Sasuke replayed the moment in his mind. Kakashi had thrown the kunai first, then disappeared and reappeared beside it without ever crossing the distance.
He had once read about a technique like that in a file on the Fourth Hokage.
"That was..."
"The Flying Thunder God Technique!"
Naruto spoke before Sasuke could finish, his attention fixed on the three-pronged kunai in Kakashi's hand.
"That was my father's technique."
"You're only half right, Naruto."
Kakashi held up the kunai.
"The Flying Thunder God Technique was created by the Second Hokage. Your father refined it and became known throughout the Ninja World for using it."
Naruto had always assumed Minato created the technique himself.
"So the Second Hokage invented it, but my father was better at using it?"
"That's one way of putting it."
By then, Sakura was no longer listening to the explanation.
"What did you just say?"
"About the Flying Thunder God?" Naruto asked.
"No. You said it was your father's technique."
"Yeah." Naruto scratched his cheek.
"The Fourth Hokage was your father?"
Naruto looked a little uncomfortable. "Shinichi told me a few years ago. Before that, I didn't know who my parents were."
Sakura and Sasuke both fell silent. They remembered how people used to whisper about Naruto and avoid him because they believed he was the Nine-Tails.
The boy the village had rejected was the son of the man who had died protecting it.
"So you really are the Fourth Hokage's son..."
Naruto gave an awkward laugh. "Why are you looking at me like that? I'm still the same person."
"You're still a loud idiot."
Naruto immediately turned toward Sasuke. "What did you say?!"
Kakashi cut them off before the argument could begin. He tapped the bells at his waist, making them ring.
"You can discuss Naruto's family later. The test is still going on, and none of you has taken even one."
Naruto stared at the bells.
"How are we supposed to take them now? You can disappear whenever we get close! Using the Flying Thunder God Technique against us is cheating!"
"Calling it cheating won't help you pass."
Naruto opened his mouth but could not come up with an answer.
"You weren't planning to quit over that, were you?" Sasuke asked.
"Who said I was quitting?"
"Then stop complaining and think."
Sasuke watched Kakashi through his Sharingan. The Flying Thunder God Technique had allowed him to escape their attack, but using it had to come at a cost.
"Every time he teleports, he consumes chakra."
Sakura picked up on his point immediately. "And the Sharingan is already draining him. If we keep forcing him to use the Flying Thunder God..."
"Then sooner or later, he'll run out." Naruto grinned. "All we have to do is keep attacking."
"You're not wrong," Kakashi admitted. "My reserves are already running low, and the Flying Thunder God Technique consumes more chakra than an ordinary movement technique."
Naruto looked pleased, but Kakashi continued.
"Of course, I knew that would be a problem."
He raised his forehead protector, revealing a purple diamond-shaped mark in the center of his forehead.
"The Yin Seal..." Sakura stared at the mark. "You learned that too?"
"I learned it to support the Flying Thunder God Technique. I can't store nearly as much chakra as you can because the Sharingan is always draining my reserves, even when I'm not using it."
Kakashi paused.
"But what I managed to store should be enough for this test."
The seal opened, and dark lines spread outward from the diamond. Stored chakra poured into Kakashi's body, quickly restoring what he had used during the fight.
Through his Sharingan, Sasuke could see Kakashi's reserves filling again.
"Fine," Naruto said. "Then we'll use up the chakra in that seal too."
"The plan hasn't changed," Sakura agreed. "We keep pressuring him until he can't teleport."
The Chidori crackled to life once more in Sasuke's hand.
"Then come and take them."
...
Inside the Hokage Office, Jiraiya stared at the mark on Kakashi's forehead.
"The Yin Seal too?"
He turned to Tsunade. "When did you teach him that?"
"I didn't."
"Then how did he learn it?"
"Shinichi gave him the training scroll. Kakashi learned it on his own."
Jiraiya returned his attention to the crystal ball. Chakra was flowing from the seal and restoring what Kakashi had used during the fight.
"The Flying Thunder God Technique and the Yin Seal... He mastered both in only two years."
"Kakashi was always talented," Hiruzen replied. "He became a Chūnin and a Jōnin younger than most, then earned his place among the best in the Anbu. After the war, he simply stopped applying himself the way he once had."
Kakashi had never stopped serving the village, but after losing Obito, Rin, Minato, and Kushina, he had spent years doing little more than carrying out his duties.
Jiraiya turned to Shinichi.
"I understand why he wanted to learn the Flying Thunder God Technique. It was Minato's technique. But why did you give him the Yin Seal as well?"
"The Flying Thunder God consumes too much chakra for Kakashi to use repeatedly. The seal covers that weakness."
"That explains the Yin Seal. Why did you have him learn the Flying Thunder God in the first place?"
"Obito's space-time ninjutsu is difficult to counter. Kakashi carries his other Sharingan, so I wanted to see whether another space-time technique would give him a way to fight it."
"Sharingan against Sharingan," Hiruzen said. "And space-time ninjutsu against space-time ninjutsu."
"That was the idea."
Shinichi was not sure Kakashi could learn the Flying Thunder God Technique. At first, it was just a test.
But once Kakashi decided to bring Obito back, he trained very hard. In two years, he learned both the Flying Thunder God Technique and the Yin Seal, doing better than Shinichi expected.
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