In a corner of Konoha, Naruto and Sasuke were doing their daily training.
"Naruto."
Sasuke suddenly spoke. "I feel like I'm running low on chakra. Ask Master if there's anything I can do about it."
After his earlier battle with Itachi, Sasuke had realized that he had a serious weakness.
"Master says he knows."
Naruto answered at once, then made a Shadow Clone to serve as Master's temporary body. Once that was done, he was about to get back to his own training.
"Hold on."
Master stopped Naruto. "Next, I'm going to apply a Sealing Jutsu to Sasuke. Watch closely. This is a chance for you to learn, too."
Naruto said, "Oh," and obediently stood to the side.
Master said to Sasuke, "After all your training, your mental energy is strong enough, but your physical energy hasn't kept up, so your total chakra is too low."
"I know."
Sasuke nodded. "That's why I'm asking if there's a brutal training method like the one I did before, something that can make my body stronger quickly."
"There is. You just need to repeatedly damage and repair your body over a short period."
Master continued, "But the process is extremely painful. I'm certain you won't be able to endure it. You'll go mad."
"Can I give it a try?"
Sasuke was a little afraid, but he didn't want to give up just like that. "I managed to stick with the training that rapidly strengthened my mental energy."
Master nodded calmly. "Then let's try it."
Two seconds later, Sasuke let out a miserable howl.
Five seconds later, Sasuke was sprawled on the ground, drenched in sweat and looking terrified.
"You couldn't last even three seconds?"
Master said, "To strengthen your body quickly, you'd have to endure that kind of pain for at least three