After everyone had eaten their fill and found places to rest, Naraku even used their bodies as teaching aids to explain to Rin some key points to pay attention to in complex Medical Ninjutsu.
As a genius who mastered the Mystical Palm Technique in a month, his level was more than enough to guide others.
As for why he bothered with all this... if he didn't teach her hand-in-hand quickly, where would there be an opportunity once they were on the battlefield?
What if Kakashi got injured, and Rin couldn't save him? What then?
He couldn't just fly to Kakashi's side, could he?
So, from the moment he could move freely in the village, Naraku would occasionally go to where Kakashi and his team trained to deliver food and water, and while he was there, he would discuss Medical Ninjutsu knowledge with Rin.
By now, he could be said to have contributed greatly to Rin's current skill level.
However, there were downsides too.
At first, that kid Obito thought Naraku was interested in Rin, so he watched him with extreme tension the whole time, often coming over to cause trouble, afraid that his goddess would be snatched away if he wasn't careful.
It was only after Naraku repeatedly assured him that he had no such feelings for Rin that he reluctantly backed off, and after observing a few more times, confirmed that Naraku's words were true, and finally dropped his guard completely.
Now, just as he started to treat Shiranui Genma's injuries and spoke a few words to Rin, Naraku once again felt that familiar, prickling gaze on him.
He didn't even need to guess; he knew it must be someone reverting to his old ways, accidentally knocking over a vinegar jar.
-- Tsk, love makes people blind.
-- No, this isn't even love for Obito, is it?
-- At most, it's just a slightly more overt'secret crush'.
Muttering a few complaints about the jealous kid in his heart, Naraku held Shiranui Genma's forearm with both hands, meticulously demonstrating to Rin the key points of the Reattachment Technique for healing muscles, and incidentally, subtly widened the distance between them.
-- That should quiet him down, right, my lord?
But the gaze from behind intensified, and he felt as if two holes were about to be burned through his spine.
Naraku turned around, unable to bear it any longer, but saw that Obito wasn't staring in their direction; instead, he was angrily talking to Might Guy, possibly triggered by something the youthful man had said.
-- Hmm? Not Obito?
He repeatedly scanned his surroundings but found no suspicious areas.
Obito and Might Guy were in a chaotic mess over there, one brandishing his claws, vowing revenge, the other grinning widely and talking about youth;
Ebisu had been lying motionless since he was healed, and he was wearing sunglasses, so there was no way he could be the source of such an intense gaze;
Kakashi, on the other hand, was sitting under a tree with his head bowed, repeatedly wiping the long sword in his hand, he didn't know how many times already... probably to alleviate his anxiety.
-- Strange.
-- It couldn't be that Black Zetsu guy, could it?
"Is something wrong, Naraku-kun?"
Rin was a little surprised why he suddenly stopped and turned to look at the others behind them.
"No, nothing."
Naraku suspiciously withdrew his gaze, suppressed his doubts, and continued explaining the part he had interrupted.
After everyone had been treated, Rin looked at the two full pages of new notes in her notebook, still wanting more, recalling the feel of the actual practice earlier, and felt that she had gained a lot today, feeling more confident that she could help Obito and Kakashi in the future.
She put her notebook into her shoulder bag, bent down, and helped Naraku wrap up the bento boxes that everyone had already tidied up, using a furoshiki cloth.
"Thank you so much for teaching me so much, Naraku-kun."
"Mm, you're welcome."
Naraku responded gently, his hands not stopping, tying a beautiful bow.
-- Such an amazing and gentle Naraku-kun... fate is truly unfair to him.
Rin pursed her lips, feeling a pang of sympathy.
Having spent so much time together, she could vaguely guess why Naraku would voluntarily teach Medical Ninjutsu—after all, the Uchiha genius suffering from bloodline limit sickness was no secret in Konoha.
-- Naraku-kun must be especially worried about Kakashi.
-- If Kakashi gets injured or sick in the future, and he's no longer around... -- At least there's me, a teammate, to help.
A heavy yet sacred sense of mission pressed on her shoulders, Rin clenched her fists, secretly vowing that she would protect Kakashi even if it meant sacrificing everything.
Minato and Inuzuka Tsume had already discussed taking the afternoon off today, and now that they had eaten and treated their injuries, they directly announced their disbandment on the spot.
Kakashi, before Naraku, used his scabbard to pick up the bundle and put it on his shoulder, calling him to hurry home and rest... After his afternoon nap, Naraku woke up on time and, as agreed, called Kakashi to the Hospital to look after Sakumo.
As soon as he opened the door to the private room, Kakashi was stunned by the dense, vast, and complex array of spell patterns that covered the entire room, and subconsciously looked at Naraku with an inquiring gaze.
"This is a special Sealing Jutsu, the Senra Tensei Rinne Array."
Naraku, however, uncharacteristically wasn't looking at him; instead, he walked in, raised his hand to caress the talismans he had personally carved into the wall, feeling the faint, almost imperceptible energy flowing within them, continuous and stable, which inexplicably brought a sense of peace.
"It can sense tiny bits of natural energy and gather them to the array's core—which is Master."
Kakashi looked in the opposite direction of the radiating characters, and indeed, every spell chain converged on his father's Hospital bed.
"It's used to protect his body and spirit from being damaged by the passage of time."
"...Actually, I don't know if this will even work."
As he spoke, his eyelashes trembled slightly, dropping halfway, and his arm lost its strength, allowing his fingertips to glide over one character after another before falling back to his side.
"Perhaps it can? To make Master wake up sooner..."
Before he could finish, Naraku was pulled into Kakashi's embrace, his hands wrapped around his back, with such force that his clothes were squeezed and wrinkled.
"Kakashi...?"
"Idiot."
Even without understanding Medical Ninjutsu, Sealing Jutsu, or "natural energy," just by looking at the sheer number of complex array patterns, Kakashi could tell how much effort Naraku had put into it over the past few months.
While he was busy training with his teammates, going out early and returning late from missions, and even having to repeatedly postpone visiting his father... how did Naraku complete this Sealing Jutsu by himself, little by little?
How many books did he have to read, how much hardship did he endure, how many times did he have to experiment to achieve this?
He hugged him a little tighter and said in a muffled voice, "Don't always push yourself so hard."
"It's okay, Kakashi." Naraku gently patted his back, coaxing him, "Tsunade-sensei and Orochimaru-sama helped me a lot. I didn't suffer at all."
"Don't lie to me."
"..."
-- The child has grown up, he's not easily fooled anymore ~
Naraku helplessly realized that his credibility in Kakashi's heart had probably already dropped to negative points, completely bankrupt.
Even if he truly wasn't in any trouble, Kakashi probably wouldn't believe a single word of it.
-- Can't there be more trust and less suspicion between people?
Naraku thought with a huff, while still having to obediently promise that he wouldn't act recklessly again.