“No, brother, I just want to know my level in kenjutsu, so let’s not use genjutsu in our spar,” Kaida said after picking up a sword.

“Okay, since you want to know your level, I’ll help you with that. First, come and attack me with everything you’ve got,” Shisui said, activating his Mangekyō Sharingan.

Kaida nodded and went to attack Shisui, activating his two-tomoe Sharingan. His first attack was a feint toward the head, which he quickly redirected toward the ribs. However, Shisui didn’t even try to stop the feint and easily deflected the actual attack without using much force. This repeated several times, but Kaida couldn’t land a single strike on Shisui.

After 10 minutes, Kaida stopped.

“Your attacks are at the level of a chunin and might work against a jonin, but now let's see about your defense. I’m going to attack you—try to defend as best you can.”

Kaida nodded and got ready.

Shisui seemed to disappear from his spot and reappear near Kaida. This was his base speed without using any jutsu, though he did use chakra to strengthen his legs. Without his Sharingan activated, Kaida wouldn’t have been able to follow Shisui’s movements. Shisui attacked Kaida from various angles and positions—any normal person would have failed to block those strikes. But since Kaida had been practicing kenjutsu against 15 clones at once, he was able to react. He coated his body in chakra to boost his speed and strength to match Shisui.

After 10 minutes, Shisui had only landed two hits on Kaida.

“Good job, brother. Your defense is at the level of an elite jonin. I doubt anyone your age has a better defense than you,” Shisui said.

“Thank you, brother,” Kaida replied.

“But there’s one problem with your kenjutsu style. It’s very basic. While it’s good to have strong fundamentals, there’s a limit to what you can achieve with just the basics. Also, you’re not using your Sharingan to its full capacity for your kenjutsu,” Shisui said.

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“What do you mean by that, brother? I kept my Sharingan active the entire time and was able to follow your movements,” Kaida asked, confused.

“That’s the issue. You can see your enemy’s movements with the Sharingan, but you’re not using that to your advantage. When we defended against each other’s attacks, did you notice any difference in how we did that?” Shisui asked.

“Yes, brother. You used much less force to defend against my attacks. Most of the time, you just deflected my strikes with a touch of your sword, while I had to use much more effort to defend against yours,” Kaida replied.

“Exactly. Since I could see your muscle movements, I could predict where to apply just enough force to deflect your attack with minimal effort. This is the Uchiha kenjutsu technique, where we push the Sharingan to its limit,” Shisui explained.

“I thought I was using my Sharingan skillfully, but now I realize I wasn’t. Looks like I have to add this to my to-do list,” Kaida said.

“Well, since you use your shadow clones for genjutsu practice, you have some free time during these three days, right?” Shisui asked.

“Yes, brother,” Kaida replied.

“Then I can teach you some of this if you’d like,” Shisui offered.

“You’re the best brother in the world!” Kaida shouted, his face lighting up with a big smile.

“I know that, but for now, let’s focus on genjutsu,” Shisui said.

Kaida nodded and created 80 shadow clones, each of them sent to catch a mouse for practice. After a while, they returned with over 150 mice. At this point, the mice in the Uchiha compound feared Kaida more than they feared the cats.

With everything ready, Shisui began his explanation.

“As you already know how to extract memories from enemies' brains, and you’ve learned the basics of making them see things that don’t exist, now we’re going to target the area of the brain that controls conscious thought. Just like with memory extraction, but this time, you’ll slow its function by covering that part with your chakra and circulating it like this. This will make them unable to think for a second, and in that moment, you’ll feed the information you want into their brain. Keep in mind, this won’t work on someone with equal or greater strength than you. If you’re a jonin, the best you could manage might be a chunin,” Shisui explained.

“Then is this even useful in real life?” Kaida asked.

“In combat, not much on its own. But if you want to gather information, make someone attack their allies to create an opening, or tame some ruffians on the street, this technique is perfect,” Shisui said.

Kaida nodded in understanding, and Shisui continued.

“Now, here’s how you do it,” Shisui said, performing the genjutsu on a rat. Kaida watched closely.

After the process was complete, Shisui said, “I’ve implanted a memory in this rat that you’ve cared for it since its childhood. Now let’s see how it behaves.” Shisui released the rat, and it ran toward Kaida, rubbing its head against his leg.

“See? That’s the power of this genjutsu. Now let me undo this, or you’ll have to make it your pet,” Shisui said, reversing the memory he had implanted.

“There are so many ways we could use this jutsu!” Kaida exclaimed, impressed.

“Yep. Only your imagination is the limit,” Shisui said.

“Should I start practicing now?” Kaida asked.

“No, there’s one last thing to teach you. Even though I said this won’t work on someone powerful, you can still try to make them unconscious. Here, let me show you,” Shisui said, using a rat to demonstrate how to knock out an enemy.

“This can also be done on allies if they’re wounded and in too much pain, as it doesn’t have any lasting effects. Now, do you have any questions?” Shisui asked.

“No, brother,” Kaida replied.

“Good. Start practicing, and I’ll come back at 4 AM. Then I’ll teach you kenjutsu too,” Shisui said.

“Thanks, brother,” Kaida said.

Shisui nodded and used the Body Flicker Jutsu to return home.