The sun was setting, casting a warm orange glow on the training grounds where Kakashi and Shin were engaged in an intense swordplay session. Since Naruto, Hinata, and Koushin had left to train in their own summon realms, Kakashi had decided to take up Koushin's suggestion and re-cultivate his Kenjutsu skills with Shin, who had a natural talent for sword arts.

"Remember, Shin, focus on your footwork and control your breathing," Kakashi advised, his voice muffled by his iconic mask.

Shin nodded, his eyes locked on Kakashi's every move, analyzing and trying to emulate his teacher's fluid movements. Much like Sai, Shin was socially awkward, a result of his childhood spent in ROOT. To cope with this, he had begun to imitate Kakashi.

“Koushin must have selected Kakashi, since we look a little bit alike. Like how Gai and Lee look so similar. This must be one of the requirements for selecting a pupil. I have gray hair too. Koushin is so wise. I still have much to learn.” Shin thought, as he balled his fist in determination.

Over the following weeks, Shin's transformation into a mini-Kakashi occurred gradually. It began with subtle changes that went almost unnoticed.

One day, Kakashi spotted Shin wearing a mask, which he found peculiar since it wasn't a necessity for him.

"Shin, what's with the mask?" Kakashi asked, raising an eyebrow.

"Oh, um, I thought it might help me focus better during training," Shin replied hesitantly, trying to come up with a plausible explanation. ‘Since Kakashi didn’t give me the mask, he must have wanted me to come up with this idea. Probably Gai did the same for Lee. I must try my best to imitate Kakashi Sensei. This way, I can learn this new art!”

Kakashi chuckled. "Well, if it helps, I suppose there's no harm in it."

A few days later, Kakashi noticed that Shin's forehead protector had been adjusted to hang at an angle, covering just one eye. He couldn't help but smile at Shin's commitment to mimicking him.

As the days went by, Shin's emulation of Kakashi became more pronounced. One afternoon, while they were taking a break from their intense training, Kakashi spotted Shin flipping through a book, seemingly engrossed in its contents.

Curiosity piqued, Kakashi approached Shin and asked, "What are you reading there, Shin?"

Shin looked up, startled, and quickly closed the book. "Oh, uh, nothing much. Just something I found."

Kakashi's heart skipped a beat as he caught a glimpse of the book's cover, which looked strikingly similar to his infamous Icha Icha series. Horrified, he thought, "Has Shin somehow gotten his hands on one of those?!"

Determined to get to the bottom of it, Kakashi casually inquired, "Mind if I take a look?"

Shin hesitated for a moment before reluctantly handing over the book. To Kakashi's immense relief, he discovered that the book was entirely blank.

"Shin, why are you carrying around a blank book?" Kakashi asked, trying to suppress his amusement.

"Well, I noticed you always have a book with you, so I thought it might be a good idea to do the same," Shin explained sheepishly. "But I didn't want to get distracted during training, so I figured a blank book would be best."

Kakashi burst into laughter. "You really are dedicated to copying me, aren't you? Well, at least you're keeping your focus on training."

Shin blushed, feeling both embarrassed and proud of his efforts to emulate his sensei. Their bond grew stronger as their training continued, and with each passing day, Shin's transformation into a mini-Kakashi became even more apparent.

As they continued to spar, Kakashi decided to introduce Shin to the new technique that Koushin had devised for them. He explained, "The technique is called Raijin's Calligraphy. It's a unique blend of swordsmanship, Fuinjutsu, and Lightning Release."

Shin's eyes widened with interest, eager to learn more.

Kakashi continued, "We'll channel our Lightning Release chakra into our swords, enhancing their cutting power. Then, using swift, precise strikes, we'll carve directly onto our opponents' bodies."

Shin's mind raced, trying to imagine how the technique would look and work in practice. The technique required swift and precise strikes that left no room for mistakes. Although the technique itself was deadly, what made it most powerful was the second part, and without being precise, the second part was useless.

"But remember," Kakashi warned, "this is just an introduction. The technique's true power and mechanics will work only if you manage to finish the strikes."

Shin nodded, his determination burning brighter than ever. He couldn’t let Kakashi down. Since his Sensei was working hard to teach him, he had to learn to the best of his abilities.

Over the next few weeks, their training sessions were filled with laughter and lighthearted banter, as Shin continued to mimic Kakashi's mannerisms. At one point, Kakashi even found Shin attempting to walk his ninken, only to realize that Shin didn't have any dogs of his own.

"Shin, what are you doing?" Kakashi asked, holding back a chuckle.

"I'm, uh, walking my ninken," Shin replied sheepishly, holding a leash that was attached to a dog from the Inuzuka Clan.

Kakashi couldn't help but laugh. "Well, at least you're committed to the act! But I hope you didn’t kidnap the ninken."

“No sensei, they even offered to pay me, but I didn’t want it.” Shin shook his head.

“Fine, fine. After a while, you can try to sign a summoning contract with my ninken. But you need to get their approval, alright?”

“Really?” Shin asked with his eyes shining.

“Yeah, yeah, really.” Kakashi shook his head in amusement.

As the days turned into weeks, the bond between Kakashi and Shin grew stronger, and Shin's skills improved tremendously. Their training sessions were a blur of electrified swords, glowing sealing formulas, and the occasional burst of laughter as Shin continued to mimic Kakashi's every move.

And while the full potential of Raijin's Calligraphy remained a mystery, one thing was certain: Kakashi and Shin had developed a unique and powerful technique that would leave their opponents quaking in fear. Their dedication to mastering it, coupled with their shared sense of humor, made them an unstoppable duo – and quite the entertaining pair to watch.